Scientific Articles

By selecting a field of Application
By selecting a product
By typing in your keyword : (Keyword can be a particular word, an author, a journal, etc.)
184 articles found

B3342 – Effect of microbial transglutaminase treatment on thermal stability and pH-solubility of heat-shocked whey protein isolate

Whey protein isolate (WPI) dispersions (5% protein, pH 7.0) were subjected to heat-shock at 70 °C for 1, 5 and 10 min. The heat-shocked WPI dispersions were treated with microbial transglutaminase (MTGase) enzyme, and thermal properties and pH-solubility of the treated proteins were investigated. Heat-shocking of WPI for 10 min at 70 °C increased the thermal denaturation temperature (Td) of ?-lactoglobulin in WPI by about 1.5 °C. MTGase treatment (30 h, 37 °C) of the heat-shocked WPI significantly increased the Td of ?-lactoglobulin by about 6.3–7.3 °C when compared with heat-shocked only WPI at pH 7.0. The Td increased by about 13–15 °C following pH adjustment to 2.5; however, the Td of heat-shocked WPI was not substantially different from heat-shocked and MTGase-treated WPI at pH 2.5. Both the heat-shocked and the heat-shocked-MTGase-treated WPI exhibited U-shaped pH-solubility profiles with minimum solubility at pH 4.0–5.0. However, the extent of precipitation of MTGase-treated WPI samples at pH 4.0–5.0 was much greater than all heat-shocked and native WPI samples. The study revealed that while MTGase cross-linking significantly enhanced the thermal stability of ?-lactoglobulin in heat-shocked WPI, it caused pronounced precipitation at pH 4.0–5.0 via decreasing the hydrophilic/hydrophobic ratio of the water-accessible protein surface.
Srinivasan Damodaran, Kingsley K. Agyare, Food Hydrocolloids 30 (2013) 12-18

B3339 – Relationship between meat toughness and properties of connective tissue from cows and young bulls heat treated at low temperatures for prolonged times

The aim of the current study was to elucidate whether cows and young bulls require different combinations of heating temperature and heating time to reduce toughness of the meat. The combined effect of heating temperature and time on toughness of semitendinosus muscle from the two categories of beef was investigated and the relationship to properties of connective tissue was examined. Measurements of toughness, collagen solubility, cathepsin activity and protein denaturation of beef semitendinosus heated at temperatures between 53°C and 63°C for up to 19 1/2 h were conducted. The results revealed that slightly higher temperatures and prolonged heating times were required to reduce toughness of semitendinosus from cows to the same level as in young bulls. Reduced toughness of semitendinosus as a result of low temperature for prolonged time is suggested to result from weakening of the connective tissue, caused partly by denaturation or conformational changes of the proteins and/or by solubilization of collagen.
Line Christensen, Per Ertbjerg, Hanne Løje, Jens Risbo, Frans W.J. van den Berg, Mette Christensen, Meat Science 93 (2013) 787–795

B3336 – Structural studies on matrices of deacylated gellan with polydextrose

The effect of varying concentrations of co-solute (polydextrose) on thermomechanical and physicochemical properties of deacylated gellan matrices is presented. Modulated differential scanning calorimetry, micro differential scanning calorimetry, small deformation dynamic oscillation in shear, Fourier transform infrared spectroscopy, wide angle X-ray diffraction and environmental scanning electron microscopy have been used to investigate the structural transformations in aqueous, low-solid and condensed systems. There was a rise in values of storage modulus as the level of co-solute was increased, followed by a significant decline at intermediate concentrations, with high modulus values being regained as more of the co-solute was incorporated. These results confirm the hypothesis of a structural transformation from a highly enthalpic aggregated assembly in the aqueous/low-solid environment to a lightly cross linked polysaccharide network in the high solids regime. Time-temperature superposition (TTS) phenomena observed for amorphous synthetic polymers have been utilised to generate master curves of viscoelasticity, which afforded rationalisation of results on the basis of the free volume theory.
Vinita Chaudhary, Darryl M. Small, Stefan Kasapis, Food Chemistry 137 (2013) 37–44

B3335 – Effect of high pressure processing on rheological and structural properties of milk–gelatin mixtures

There is an increasing demand to tailor the functional properties of mixed biopolymer systems that find application in dairy food products. The effect of static high pressure processing (HPP), up to 600 MPa for 15 min at room temperature, on milk–gelatin mixtures with different solid concentrations (5%, 10%, 15% and 20% w/w milk solid and 0.6% w/w gelatin) was investigated. The viscosity remarkably increased in mixtures prepared with high milk solid concentration (15% and 20% w/w) following HPP at 300 MPa, whereas HPP at 600 MPa caused a decline in viscosity. This was due to ruptured aggregates and phase separation as confirmed by confocal laser scanning microscopy. Molecular bonding of the milk–gelatin mixtures due to HPP was shown by Fourier-transform infrared spectra, particularly within the regions of 1610–1690 and 1480–1575 cm?1, which reflect the vibrational bands of amide I and amide II, respectively.
Anastasia Fitria Devi, Li Hui Liu, Yacine Hemar, Roman Buckow, Stefan Kasapis, Food Chemistry 141 (2013) 1328–1334

B3334 – Rheology and synergy of ?-carrageenan/locust bean gum/konjac glucomannan gels

The rheology and melting of mixed polysaccharide gels containing konjac glucomannan (KGM), locust bean gum (LBG) and K-carrageenan (KC) were studied. Synergy-type peaks in the Young's modulus at optimal mixing ratios were found for both KC/LBG and KC/KGM binary gels at a fixed total polysaccharide content (1:5.5 for LBG:KC and 1:7 for KGM:KC). The Young's modulus peak for KC/KGM was higher than for KC/LBG gels. The same stoichiometric mixing ratios were found when either LBG or KGM was added to KC at a fixed KC concentration, where the Young's modulus increased up to additions at the stoichiometric ratio, but leveled off at higher LBG or KGM additions. Addition of KGM or LBG to the 2-component gels beyond the stoichiometric (optimal) mixing ratio at a fixed total polysaccharide content led to a decrease in the Young's modulus and an increase in the rupture strain and stress in extension, and both trends were stronger for KGM than for LBG. Differential scanning calorimetry of the gels revealed the development of a second melting peak for the KC/KGM gels that increased with KGM addition up to higher KGM contents than the stoichiometric ratio. For the KC/LBG gels, only a slight broadening and shift to a higher temperature were observed. When the three polysaccharides were mixed, the DSC endotherms reflected only the main features of the interaction between KC and KGM, and the same was true for the fracture in extension. The different trends led to higher Young's moduli at intermediate KC concentrations when a 1:1 addition of LBG: KGM was used than when either only KGM or LBG was added at a fixed total polysaccharide concentration. This suggests that no special interactions arise when the three polysaccharides are mixed and the binding mechanisms are simply a sum of the bindings observed for KC/KGM and KC/LBG two-component gels.
Tom Brenner, Zheng Wang, Piyada Achayuthakan, Tetsuya Nakajima, Katsuyoshi Nishinari, Carbohydrate Polymers 98 (2013) 754– 760

B3330 – Effect of whey protein agglomeration on spray dried microcapsules containing Saccharomyces boulardii

This work investigates the effect of whey protein agglomeration on the survivability of Saccharomyces boulardii within spray dried microcapsules. It attempts to go beyond phenomenological observations by establishing a relationship between physicochemical characteristics of the polymeric matrix and its effect on probiotic endurance upon spray drying. It is well known that this type of thermal shock has lethal consequences on the yeast cells. To avoid such undesirable outcome, we take advantage of the early agglomeration phenomenon observed for whey protein by adjusting the pH value of preparations close to isoelectric point (pH 4-5). During the subsequent process of spray drying, development of whey protein agglomerates induces formation of an early crust, and the protein in this molten globular state creates a cohesive network encapsulating the yeast cells. It appears that the early crust formation at a given sample pH and temperature regime during spray drying benefits the survivability of S. boulardii within microcapsules.
Diep Duongthingoc, Paul George, Lita Katopo, Elizabeth Gorczyca, Stefan Kasapis, Food Chemistry 141 (2013) 1782–1788

B3294 – Characteristics and chemical composition of date palm (Phoenix canariensis) seeds and seed oil

Studies were conducted on properties of seeds and oil extracted from fully ripened Phoenix canariensis date seeds. The percentage composition of the P. canariensis seeds found is: ash 1.18%, oil 10.36%, protein content 5.67%, total carbohydrate 72.59% and moisture 10.20%. The major nutrients (mg/100 g of oil) determined were: potassium (255.43), magnesium (62.78), calcium (48.56) and phosphorus (41.33). The physicochemical properties of the oil observed include: the saponification number 191.28; the iodine number 76.66, the p-anisidine value 3.67; the peroxide value 3.62 meq/kg; the unsaponifiable matter content 1.79%, the free fatty acids content 0.59%; the carotenoid content 5.51 mg/100 g; the chlorophyll content 0.10 mg/100 g and the refractive index 1.45. The main fatty acids of oil were oleic (50.10%), linoleic (19.23%), lauric (10.24%). palmitic (9.83%) and stearic (7.51%). The main triacylglycerols found in P. canariensis seed oil were: LaMM + LaLaP (18.9%), LaMP + MMM (15.31%) and LaOO + PLL + MPL (12.86%). The DSC melting curves revealed that: melting point = 3.71 °C and melting enthalpy = 62.08 J/g. The sterol marker, ?-sitosterol, accounted for 76.06% of the total sterols content in the seed oil followed by campesterol (8.89%) and ?5avenesterol (8.79%). ?-Tocotrienol was the major tocol (66%) with the rest being ?-tocotrienol and ?-tocopherol.
I. Nehdi, S. Omri, M.I. Khalil, S.I. Al-Resayes, Industrial Crops and Products 32 (2010) 360–365

B3286 – Synergistic effect of high pressure processing and Lactobacillus casei antimicrobial activity against pressure resistant Listeria monocytogenes

The purpose of this study was to evaluate combinations of high pressure processing (HPP) and Lactobacillus casei antimicrobial activity against Listeria monocytogenes strains with variation in pressure resistance in culture and in a food model. In culture, combination of HPP (350 MPa, for 1–20 min) and Lb. casei cell extract (CE, 32 CEAU/ml) showed a significant synergistic bactericidal effect (P < 0.05) and the combination treatment decreased pathogen’s population >5 log10 CFU/ml. Synergy between CE and HPP was most evident in the pressure-resistant strain, OSY-8578. Similar result was observed in meat products where high pressure (500 MPa for 1 min), and high-activity CE (100 CEAU/g) caused >5 log reduction in the viability of L. monocytogenes Scott A. The combination treatment resulted in the absence of peaks associated with cellular components in DSC thermogram suggesting that the presence of CE may have caused a considerable damage to cellular components during the high pressure treatment.
Hyun-Jung Chung, Ahmed E. Yousef, New Biotechnology Volume 27, Number 4 September 2010

B3278 – Composition and quality of rice flour-fish mince based extruded products with emphasis on thermal properties of rice flour

Extruded products with rice flour and ribbonfish mince mixture were prepared using a twin-screw extruder with varying barrel temperatures, and the quality of the final product was evaluated. The optimum process conditions, as revealed by organoleptic evaluation for acceptable final products, included a barrel temperature of 90C and fish mince concentration of 10%. The amino acid composition of final extruded product revealed a higher content of lysine, glutamic acid and leucine. The increase in expansion ratio and water absorption capacity of extrudate with 10% fish mince was significantly (P < 0.05) influenced by barrel temperature. The breaking strength of the extrudate increased significantly (P < 0.05) with addition of 20% fish mince. The differential scanning calorimetric studies of rice flour indicated the peak value of endothermic transition at 64.73C, which is specific for short grain rice flour. The dynamic rheological testing of rice flour solution (10%) indicated gelatinization temperature at 63.3C.
A.O. Dileep, B.A. Shamasundar, P.K. Binsi, N.K. Howell, Journal of Texture Studies 41 (2010) 190–207

B3277 – A proposed mechanism of tenderising post-rigor beef using high pressure–heat treatment

Tenderness of beef M. Sternomandibularis was tough when cooked from both raw, and when previously heated (60 °C, 20 min), whereas a significant improvement in tenderness was achieved when pressure–heat (P–H) treated muscle (200 MPa, 60 °C, 20 min) was cooked. In order to determine the mechanism for this improvement, connective tissue, myofibrillar and sarcoplasmic proteins, were separated into three fractions and studied with regard to their solubilisation, denaturation and aggregation, degradation and strengthening of protein structures for the three treatments (raw, heated and H–P treated). Measurements included DSC, SDS–PAGE, surface hydrophobicity, and the appearance, length and width of myofibres (light microscopy). For the connective tissue fraction, heat solubility was determined. It is suggested that the mechanism for this improvement in tenderness is the formation of a strengthened myofibrillar structure that, when sheared by mastication, allows the crack to pass through the meat rather than dissipate into a more visco-elastic structure. In this way a more brittle fracture is achieved and the meat is perceived as more tender. The pre-requisite is that adequate enzymatic activity has occurred. It is suggested that cathepsins are responsible.
Anita Sikes, Eva Tornberg, Ron Tume, Meat Science 84 (2010) 390–399

B3269 – Influence of protein heat treatment on the continuous production of food foams

The influence of WPI heat treatment on the continuous production of food foams was investigated using a model food including xanthan. The temperature of heat treatment was increased up to 90 °C using a plate heat exchanger; a rotor–stator unit was used for aeration purpose. The aim was to determine the interplay between heat-induced protein denaturation and aggregation, and the process parameters of aeration operation: namely, rotation speed, residence time and operating pressure. Microstructure, texture and stability of 200% overrun foams were analysed. Experimental results demonstrated that foam microstructure, namely overrun and bubble size distribution, was governed by the process parameters of aeration and depended only slightly on thermal treatment. Conversely, foam stability was strongly improved by heat treatment. These trends agreed roughly with results obtained in a batch kitchen mixer, but batch methods remained unable to predict quantitatively the behaviours observed in continuous aeration operation.
I. Nicorescu, C. Vial, C. Loisel, A. Riaublanc, G. Djelveh, G. Cuvelier, J. Legrand, Food Research International 43 (2010) 1585–1593

B3268 – Composition and quality attributes of conventionally and organically farmed Pangasius fillets (Pangasius hypophthalmus) on the German market

A range of conventionally and organically farmed Pangasius or sutchi catfish fillets available on the German market were analysed to compare both composition and quality. Differentiation of Pangasius hypophthalmus from Pangasius bocourti was achieved by RFLP-SSCP analysis. The protein content of conventionally farmed fillets ranged between 13.3 and 15.7%, whereas organically produced fillets had significantly higher protein contents of between 17.0 and 17.4%. No difference in the fat content between farming methods was observed, which varied between 1.4 and 3.2%. Polyunsaturated fatty acids represented about 24% of the total fatty acids with a high level of linoleic acid. The comparison of the proximate composition indicated that water was added to most of the conventionally farmed products, in different amounts, as well as water-binding capacity enhancing additives. Differential scanning calorimetry was used to demonstrate the presence of polyphosphate on muscle proteins. Differences in texture, water-binding capacity and colour are discussed.
Horst Karl, Ines Lehmann, Hartmut Rehbein, Reinhard Schubring, International Journal of Food Science and Technology 2010, 45, 56–66 doi:10.1111/j.1365-2621.2009.02103.x 2010

B3231 – Investigation of the diffusion of dyes in agar gels

An experimental set-up and a measurement technique were developed so that diffusion in model foods (gels of agar) could be visualised and quantified. The diffusion of aqueous solutions of varying concentrations of two dyes (rhodamine 6G and methylene blue) in gels of agar was followed in situ at three temperatures (30, 50, 70 °C) until equilibrium was reached. The nature of the diffusion process (in terms of the amount of dye diffused into the gel) was studied using image analysis techniques. The diffusion coefficient, D, was estimated using Fick’s second law of diffusion and found to be ?10?10 m2 s?1. The effect of the size of the diffusing molecule, as well as that of the processing temperature on diffusion was investigated and found to be significant.
K. Samprovalaki, P.T. Robbins, P.J. Fryer, Journal of Food Engineering 111 (2012) 537–545

B3228 – Functionality of pork meat proteins: Impact of sodium chloride and phosphates under high-pressure processing

The effect of high-pressure treatment (350 MPa, 6 min, 20 °C) combined with sodium chloride (1.5–3.0%) and phosphates (0.25–0.5%) on the texture, water retention, color and thermal properties was assessed in pork meat batters. A principal component analysis was used to identify the relationship between thermal denaturation and the functional properties of pork meat proteins. The hardening effect of high pressure was correlated with the appearance of a high-pressure-induced myofibrillar protein structure. The structure was destabilized by sodium chloride and phosphates, which counteracted the high-pressure effect on pork batter texture. Cooking yield and water-holding capacity were improved by the interaction between sodium chloride and phosphates under pressure. The interaction between high pressure, sodium chloride and phosphates also changed the color of the cooked pork meat batters. The modifications of these technological properties could be related to protein denaturation through the effects of high pressure, salt, phosphates and the appearance of a salt-induced component.
G. Villamonte, H. Simonin, F. Duranton, R. Chéret, M. de Lamballerie, Innovative Food Science and Emerging Technologies 18 (2013) 15–23

B3224 – Effect of composition of commercial whey protein preparations upon gelation at various pH values

The major goal of this research effort was to comprehensively characterize various whey protein products available in the market — including one whey protein isolate (WPI) and three whey protein concentrates (two forms of WPC 80, and WPC 50), with regard to the effects of specific components (e.g. lecithin and minerals) and concentration of ?-lactoglobulin (?-Lg) and ?-lactalbumin upon thermal and gelation properties at various pH values (using micro differential scanning calorimetry, ?DSC, and oscillatory rheometry). At pH values far from the isoelectric point of whey proteins, denaturation and aggregation appeared as one single endothermic peak in the corresponding ?DSC heating thermograms, for WPI and both WPC 80; however, they appeared as separate transitions at pH 5. Acidic conditions increased the temperature of occurrence of the dominant endothermic transition associated to ?-Lg, thus increasing the thermal stability of WPI, WPC 80A and WPC 80B. Gelation took place at the lowest temperature when pH was set at 5. WPI, WPC 80A and WPC 80B exhibited the highest G? values at pH 5 — whereas WPI led to stronger gels than WPC, irrespective of pH. In the case of WPC 50, gelation did not occur at all.
Óscar L. Ramos, Joana O. Pereira, Sara I. Silva, Maria M. Amorim, João C. Fernandes, José A. Lopes-da-Silva, Manuela E. Pintado, F. Xavier Malcata, Food Research International 48 (2012) 681–689

B3202 – Water sorption and plasticization of an amorphous galacto-oligosaccharide mixture

Food-grade galacto-oligosaccharides (GOS) are commercially available as transparent syrups or dried powders. Food powders can be found in an amorphous metastable state which is very sensitive to changes in temperature and moisture content. In this work the impact of water content on thermal behavior and relative humidity on water sorption behavior of amorphous GOS powders were studied. Results from differential scanning calorimetry (DSC) and sorption isotherms suggest that GOS mixture studied, with high content of oligosaccharides, has low ability to crystallize. A dramatic decrease in the stability of GOS powders occurred above critical water content (12–14 g/100 g) and corresponding critical water activity (0.55–0.62). Above these conditions GOS powder lost its amorphous character, collapsed and shrank, as the powder became a transparent “solution-like” material. The knowledge about the physicochemical changes, acquired during the present study, should be used to a proper control of processing and storage conditions to achieve and maintain optimum powder quality with desired properties.
Duarte P.M. Torres, Margarida Bastos, Maria do Pilar F. Gonçalvese, Carbohydrate Polymers 83 (2011) 831–835 José A. Teixeirab, Lígia R. Rodrigues

B3164 – Characteristics, chemical composition and utilisation of Albizia julibrissin seed oil

The physicochemical characteristics, fatty acid and triacylglycerol compositions, DSC profile and UV/vis spectrum of oil extracted from Albizia julibrissin seeds were determined in this study. The oil content and the moisture of the seeds were 10.50% and 1.56%. The free fatty acid, the peroxide value, the p-anisidine value, the saponification value, the iodine value were 2.54%, 6.61 mequiv. O2/kg of oil, 1.98, 190.63 (mg KOH/g) and 111.33 (g/100 g of oil), respectively. The specific extinction coefficients K232, K268 were 7.55 and 0.96, respectively. Linoleic acid (C18:2, 58.58%), palmitic acid (C16, 13.86%) and oleic acid (C18:1, 10.47%) were the dominant fatty acids in the A. julibrissin seed oil. LLL (36.87%), OLL (21.62%), PLL (16.69%) and PLO + SLL (8.59%) were the abundant triacylglycerol representing > 83% of the seed oil (L: linoleic, O: oleic, P: palmitic, S: stearic). The DSC melting curves reveal that: melting point = ?14.70° C and melting enthalpy = 54.34 J/g. A. julibrissin seed oil showed some absorbance in the UV-B and UV-C ranges. The results of the present analytical study show that A. julibrissin is a promising oilseed crop, which can be used for making soap, hair shampoo and UV protectors. Furthermore, the high level of unsaturated fatty acids makes it desirable in terms of nutrition.
I. Nehdi, Industrial Crops and Products 33 (2011) 30–34

B3163 – Changes in chemical composition of Phoenix canariensis Hort. Ex Chabaud palm seed oil during the ripening process

The aim of this investigation is to compare the physicochemical properties and chemical composition of Phoenix canariensis seed oil at different stages of seed date ripening. It was demonstrated that the saponification number of the oil increases during the maturation from 179.24 to 191.28 (mg KOH/g of oil), whereas the seed oil yield, the iodine number, the p-anisidine value, the peroxide value, the acidity and the unsaponifiable matter decrease from 14.73% to 10.36%, from 89.37 to 76.66 (g/100 g of oil), from 5.51 to 3.67, from 17.66 to 3.62 (mequiv. O2/kg of oil), from 1.49% to 0.59% and from 2.72% to 1.77%, respectively. The tocol content increases as the maturity advanced. The percentages of sterols show continuous changes during ripening. The saturated fatty acid content increases throughout the ripening process. The oleic fatty acid content decreases during the seeds maturation, but increases at the end, whereas linoleic acid content initially shows an increase, and then a decrease. The total phosphorus content decreases during the period of ripening. The three samples of the seed oil show a high kinetic stability during the heating and cooling, as characterised by the differential scanning calorimetry (DSC). The DSC curves reveal an increase in the melting point from ?7.73 °C to 3.71 °C but the melting enthalpy remains the same, 62.06 J/g, during the ripening of the dates.
Imededdine Arbi Nehdi, Hedi Zarrouk, Saud Ibrahim Al-Resayes, Scientia Horticulturae 129 (2011) 724–729

B3162 – Characteristics and composition of Washingtonia filifera (Linden ex André) H. Wendl. seed and seed oil

Characteristics of seeds and oil extracted from Washingtonia filifera seeds are evaluated. The percentage composition of the W. filifera seeds is: ash 1.37%, oil 16.30%, protein content 3.46%, total carbohydrate 77.19% and moisture 3.22%. The major nutrients (mg/100 g of seeds) found in the seeds are: potassium (67.33), magnesium (34.35), calcium (187.85) and phosphorus (23.26). Physicochemical properties of the oil include: iodine value 67.33 g/100 g of oil; saponification value, 191.63 mg KOH/g of oil; refractive index (25 °C), 1.469; unsaponifiable matter, 0.83%; acidity, 0.41%; p-anisidine value, 0.87; peroxide value, 7.60 mEq O2/kg of oil; carotenoid content 14.8 mg/100 g and the chlorophyll content = 0.13 mg/100 g. W. filifera seed oil shows some absorbance in the UV-B and UV-C ranges with potential use as a broad spectrum UV protectant. The oil contains high levels of oleic acid (40.60%) followed by lauric acid (17.87%), linoleic acid (16.26%), myristic acid (11.43%) and palmitic acid (9.23%). The triacylglycerols (TAGs) with equivalent carbon number ECN 44 (20.47%) are dominant, followed by TAGs ECN 46 (16.71%), TAGs ECN 42 (15.43%) and TAGs ECN 48 (15.41%). The DSC melting curves reveal that: melting point = 2.25 °C and melting enthalpy = 82.34 J/g. ?-Tocotrienol is the major tocol (72%) with the rest being ?-tocotrienol and ?-tocotrienol. The results of the present analytical study show that W. filifera seed oil could be used in cosmetic, pharmaceutical and food products.
Imededdine Arbi Nehdi, Food Chemistry 126 (2011) 197–202

B3108 – Effect of pulsed electric field and thermal treatment on the physicochemical and functional properties of whey protein isolate

The effect of pulsed electric field (PEF) compared with thermal treatment on physicochemical properties (protein aggregation, surface hydrophobicity, contents of exposed and total sulphydryl groups, and thermal stability), and functional (emulsification and gelation) properties of whey protein isolate (WPI) was determined. Within the experimental conditions tested, PEF treatment did not affect any of the physicochemical or emulsification properties of WPI. However, the heat-induced gel strength of WPI decreased from 461 Pa to 139 and 67 Pa after PEF treatment at 30 kV cm?1 for 19.2 and 211 ?s, respectively, and the corresponding gelation times increased from 40.8 min to 43.2 and 47.9 min. This study indicates that the effect of PEF on the gelation properties of WPI may be beneficial in applications where whey protein precipitation and gelation are not desirable, such as during concentration of whey protein preparations and prior to spray drying.
Qian Sui, Hubert Roginski, Roderick P.W. Williams, Cornelis Versteeg, Jason Wan, International Dairy Journal 21 (2011) 206-213

B3107 – Structure and properties of Treculia africana, (Decne) seed starch

Starch isolated from seed flours of four Treculia africana (African breadfruit) trees ranged from 36.0 to 41.7% (w/w, flour). Digital microscopy and image particle size analysis showed smooth, small to medium elliptical granules of sizes 3.56–13.60 ?m with over 80% of the granules in the size range of 5.50–9.49 ?m. T. africana starch displayed an A-type X-ray diffraction pattern with crystallinities in the range of 40.21–43.14%. The apparent amylose content ranged from 21.2 to 23.1% while the absolute amylose content was 13.7–21.7%. The gelatinization characteristics, swelling power and amylose leaching, paste clarity, freeze thaw stability and rheological properties were studied. The gelatinization onset temperatures ranged from 71.5 to 75.1 °C, and the peak gelatinization temperatures and endothermic enthalpies were 74.5–78.8 °C and 12.22–13.99 J/g, respectively. Rheological examination of 5% starch paste over the range of shear rate 0.1–1000/s gave shear viscosities of 3.357–8.285 Pa s and rate indices of 0.44–0.53 and the mechanical spectra indicated that the gels were formed with G? > G?? over the frequency range studied. T. africana starch exhibited low level of syneresis after six freeze thaw cycles (32–38%); however, it would require modification to enhance its application in processed foods.
Louis M. Nwokocha, Peter A. Williams, Carbohydrate Polymers 84 (2011) 395–401

B3106 – Structural, physicochemical and rheological characterization of Tacca involucrata starch

Starch was isolated from white and yellow Tacca involucrata tubers and the characteristics studied. The granule morphology was the same for both starches but they differed in granule size distribution: white tacca (6.13–18.12 ?m), yellow tacca (4.19–11.98 ?m). Yellow tacca exhibited an A-type X-ray diffraction pattern but white tacca had a C-type diffraction pattern. White tacca had a slightly higher weight average Mw (2.12 × 107 g/mol) than yellow tacca (1.85 × 107 g/mol). Yellow tacca had lower gelatinization temperature, higher swelling power, higher amylose leaching and higher freeze–thaw stability compared with white tacca. However, the flow characteristics and small deformation mechanical spectra of the starch gels did not differ greatly. The high paste clarity of tacca starches at higher starch concentrations indicates a potential for application in food products like pies and puddings where clarity is desirable.
Louis M. Nwokocha, Chandra Senan, Peter A. Williams, Carbohydrate Polymers 86 (2011) 789– 796

B3105 – Comparative study of physicochemical properties of breadfruit (Artocarpus altilis) and white yam starches

Starch from seedless breadfruit (Artocarpus altilis) was isolated and its granule characteristics, structural, physicochemical and rheological properties compared with white yam starch. Both starches exhibited a B-type diffraction patterns with a crystallinity of 36.2% for breadfruit starch and 37.3% for white yam. The two starches differed in granule size distribution and morphology; while breadfruit starch consisted of small, irregular shaped and aggregated granules (2.3–8.4 ?m), white yam starch granules were large (19.2–30.8 ?m), smooth and uniformly polyhedral. The amylose content and peak gelatinization temperature were different for breadfruit starch (20.0%; 69.3 °C) and white yam starch (22. 8%; 70.2 °C). The gelatinization temperature increased while the enthalpy decreased with increase in sodium chloride concentration for both starches. The starch molecules of breadfruit have a lower weight average Mw (1.72 × 107 g/mol) compared with white yam starch (Mw = 2.32 × 107 g/mol). The swelling power (SP), amylose leaching (AML) at 95 °C, and paste clarity (PC) at 1% (w/w) of breadfruit starch (SP, 39.4 g/g; AML, 5.23%; PC, 2.25%) were lower than those of white yam starch (SP, 49.8 g/g; AML, 10.9%; PC, 12.79%). Its shear viscosity was lower but its ability to withstand viscosity breakdown was higher than white yam starch. The properties of breadfruit starch indicate it would require modification to improve water binding capacity and clarity of the paste, and reduce retrogradation. However, the small granule size of breadfruit starch makes it a candidate for application as a dusting starch.
Louis M. Nwokocha, Peter A. Williams, Carbohydrate Polymers 85 (2011) 294–302

B3104 – Gelatinization of waxy starches under high pressure as influenced by pH and osmolarity: Gelatinization kinetics, final structure and pasting properties

We investigated the influence of pH and osmolarity on the high-pressure-induced gelatinization of waxy corn and waxy rice starches in salt solutions, and the properties of the resulting gels. Gelatinization kinetics, the gel swelling power of starches, their structure and their rheological properties were studied for starch suspensions treated at 500 MPa. Gelatinization took place mostly in the first 15 min of the pressure treatment and both the gelatinization speed and the maximal level of gelatinized starch decreased with increasing osmolarity. pH had a minor influence on gelatinization kinetics differing from one starch to another. The resulting gels appeared as a mix of a gel and starch granules with a higher proportion of native granules with increasing osmolarity. Gel strength and swelling were positively correlated to their proportion of gelatinized starch. Thus, gels with different structures and gelatinization levels can be obtained under pressure depending on pH and osmolarity.
H. Simonin, C. Guyon, M. Orlowska, M. de Lamballerie, A. Le-Bail, LWT - Food Science and Technology 44 (2011) 779-786

B3103 – Comparative effect of thermal treatment on the physicochemical properties of whey and egg white protein foams

The optimization of the functionalities of commercial protein ingredients still constitutes a key objective of the food industry. Our aim was therefore to compare the effect of thermal treatments applied in typical industrial conditions on the foaming properties of whey protein isolate (WPI) and egg white proteins (EWP): EWP was pasteurized in dry state from 1 to 5 days and from 60 °C to 80 °C, while WPI was heat-treated between 80 °C and 100 °C under dynamic conditions using a tubular heat exchanger. Typical protein concentrations of the food industry were also used, 2% (w/v) WPI and 10% (w/v) EWP at pH 7, which provided solutions of similar viscosity. Consequently, WPI exhibited a higher foamability than EWP. For WPI, heat treatment induced a slight decrease of overrun when temperature was above 90 °C, i.e. when aggregation reduced too considerably the amount of monomers that played the key role on foam formation; conversely, it increased foamability for EWP due to the lower aggregation degree resulting from dry heating compared to heat-treated WPI solutions. As expected, thermal treatments improved significantly the stability of WPI and EWP foams, but stability always passed through a maximum as a function of the intensity of heat treatment. In both cases, optimum conditions for foam stability that did not impair foamability corresponded to about 20% soluble protein aggregates. A key discrepancy was finally that the dry heat treatment of EWP provided softer foams, despite more rigid than the WPI-based foams, whereas dynamically heat-treated WPI gave firmer foams than native proteins.
I. Nicorescu, C. Vial, E. Talansier, V. Lechevalier, C. Loisel, D. Della Valle, A. Riaublanc, G. Djelveh, J. Legrand, Food Hydrocolloids 25 (2011) 797-808

B3102 – Thermo- and pH-responsive polyelectrolyte complex membranes from chitosan-g-N-isopropylacrylamide and pectin

Non-stoichiometric polyelectrolyte complex membranes between chitosan-g-N-isopropylacrylamide (PNIPAm) and pectin were prepared and subjected to a thermal treatment by which ionic bonds were converted into amide bonds. Membranes are hydrophilic, with opaque appearance, but vitreous when dry. Swollen membranes undergo a sharp shrinking process with an inflexion point at 33.1 °C. Below LCST, NIPAm chains are hydrated and completely stretched. As temperature increases above LCST, NIPAm chains contract and water is expelled from the polymer matrix, giving rise to the phase transition that is associated to an endothermic peak and is fully thermoreversible. These membranes are not only sensitive to temperature, but also to the pH of the medium whose variation has no influence on LCST. Nevertheless, transition enthalpy decreases when pH increases within studied interval, showing the same trend as equilibrium swelling.
Maricarmen Recillas, Luisa L. Silva, Carlos Peniche, Francisco M. Goycoolea, Marguerite Rinaudo, Julio San Román, Waldo M. Argüelles-Monal, Carbohydrate Polymers 86 (2011) 1336– 1343

B3101 – Effect of molecular weight and chemical structure on thermal and rheological properties of gelling ?/?-hybrid carrageenan solutions

Three ?/?-hybrid carrageenan polysaccharides with distinct molecular mass and content of ?-carrageenan disaccharide units were isolated from Mastocarpus stellatus seaweeds. The viscoelastic and thermal properties of 2 wt% ?/?-hybrid carrageenan solutions with ionic strength tuned by the addition of NaCl salt were studied by means of rheological tests and differential scanning calorimetry (DSC). All solutions form a gel upon cooling. The gel elasticity decreases with the content in ?-carrageenan disaccharide units, and does not correspond to the additive elasticity of a ?- and a ?-carrageenan networks. The highest gel elasticity is obtained with the lowest molecular mass. In 0.1 M NaCl, two gelling processes are evidenced. The first increase in solution viscosity upon cooling coincides with a thermal transition process, which is assigned to a coil-to-helix conformational transition. The transition depends on both molecular mass distribution and chemical structure. The same dependencies are observed for the gel melting behaviour as all rheological and thermal processes determined are shifted to higher temperature with decreased molecular mass or increased content in ?-carrageenan disaccharide units.
Hiléia K.S. Souza, Loic Hilliou, Margarida Bastos, Maria Pilar Gonçalves, Carbohydrate Polymers 85 (2011) 429–438

B3100 – Rheology and microstructure of k-carrageenan under different conformations induced by several concentrations of potassium ion

Rheology, micro-DSC and confocal microscopy were used to study the effect of potassium ion on the viscoelastic behavior, disorder–order transition and microstructure, respectively, of ?-carrageenan in solution under different conformations at 60, 25 and 9 °C. At 60 and 25 °C the rheological behavior of 0.5% ?-carrageenan with 0–80 mmol/dm3 and 0–5 mmol/dm3 KCl, respectively, was typical of viscoelastic solutions of random coiled polymers. At 9 °C and below a critical ionic concentration of about 7.0 mmol/dm3, ?-carrageenan adopted an ordered conformation in which helical structures did not aggregate and hence did not form self-supporting gels. Changes in polysaccharide stiffness were estimated from intrinsic viscosity variations as a function of ionic content. In the ordered state, the stiffness was higher than in the disordered state, whereas a liquid-like viscoelastic behavior was still exhibited. In 0.5% ?-carrageenan at 25 °C, increasing KCl from 0 to 300 mmol/dm3 produced gels of increasing rigidity. However, above 100 mmol/dm3 such increase was marginal. Confocal images evidenced a three-dimensional network whose continuity depends on polysaccharide and salt concentrations. These observations are consistent with the rheological behavior of the self-supporting gels obtained with ?-carrageenan concentrations in the range of 0.05–1%.
M.C. Núñez-Santiago, Alberto Tecante, Catherine Garnier, Jean Louis Doublier, Food Hydrocolloids 25 (2011) 32-41

B3099 – Physical and chemical properties of ultrasonically, spray-dried green banana (Musa cavendish) starch

Ultrasonic wave propagation and the spray dryer technique were applied to study their effect on the physical and chemical properties of green banana starch. The results showed high resistant starch content, which was reduced by ultrasound treatment and also by spray drying. Both techniques increased the solubility, swelling power and water absorption capacity. The gels exhibited non-Newtonian shear-thinning behavior, since flow behavior index was less than one (n < 1). Ultrasound wave propagation reduced yield stress and consistency coefficient in starch gels. Under oscillatory shear, all gels exhibited solid-like viscoelastic behavior, storage modulus was higher than loss modulus to entire frequency range (G? > G??), which was confirmed by the Cox–Merz experiment that showed that the complex dynamic viscosity was greater than the apparent viscosity in all samples. The gelatinization temperature was mainly influenced by drying technique and ultrasound treatment reduced the amount of energy required to gelatinize the starch.
Dayane Rosalyn Izidoro, Maria-Rita Sierakowski, Charles Windson Isidoro Haminiuk, Clayton Fernandes de Souza, Agnes de Paula Scheer, Journal of Food Engineering 104 (2011) 639–648

B3097 – Rice Flour – A functional ingredient for premium crabstick

Rice flour possesses functional properties in enhancing texture and whiteness. This study was carried 2 out to evaluate rice flour as a functional ingredient for premium crabstick and develop a commercially viable recipe for premium crabstick. Physicochemical properties of crabstick pastes prepared with 42% surimi, various rice flour concentrations (0, 1, 3, and 5%), and other ingredients were evaluated. The physical properties were measured during refrigerated and frozen storage. Rice flour measured at various concentrations (5% to 40% in water) using differential scanning calorimetry (DSC) demonstrated similar patterns with an endothermic peak at around 63.5oC. During refrigerated storage up to 21 days, the strength of gel increased gradually, while cohesiveness stayed mostly unchanged. At 1% rice flour addition, fracture gel properties during 21 days of refrigerated storage showed optimum results. During frozen storage, water retention ability (WRA) gradually decreased as freeze-thaw (F/T) cycle was extended. However, the reduction was minimized as rice flour concentration increased. Two different crabstick samples (control and 1% rice flour) demonstrated no difference in strength and cohesiveness of gels. Rice flour (1%) can be used to replace various starches as a functional ingredient in premium crabstick.
Sungik Hur, Dong-Soo Kim, Cho Seung-Mock, Jae W. Park, J of Food Science and Biotechnology

B3095 – Protein denaturation and water–protein interactions as affected by low temperature long time treatment of porcine Longissimus dorsi

The relationship between water–protein interactions and heat-induced protein denaturation in low temperature long time (LTLT) treated pork Longissimus dorsi was investigated by combining low-field NMR T2 relaxometry with DSC measurements and measures of shrinkage of porcine Longissimus dorsi heated to 53 °C, 55 °C, 57 °C and 59 °C for either 3 or 20 h. Water within the myofibrils, measured by NMR T21 relaxation times, was affected by both temperature and holding time during LTLT treatment between 53 °C and 59 °C. The changes in NMR T21 relaxation times were associated with decreased fiber diameter and increased cooking loss, revealing a relationship between transverse shrinkage, water–protein interactions and cooking loss. DSC measurements revealed a concomitant decrease in ?H68 °C, which suggests impact of collagen denaturation on the retention of water within the meat during LTLT treatment. Furthermore, a decrease in ?H75 °C suggested that prolonged cooking (20 h) resulted in actin denaturation leading to decreased T21 relaxation times and higher cooking loss.
Line Christensen, Hanne C. Bertram, Margit D. Aaslyng, Mette Christensen, Meat Science 88 (2011) 718–722

B3093 – Drug release from calcium and zinc pectinate beads: Impact of dissolution medium composition

The aim of this study was to investigate drug release from calcium and zinc pectinate beads and to understand the impact of medium electrolytes during drug transfer. A potential drug carrier for colonic drug delivery (rutin) was prepared with calcium and zinc pectinate beads and was tested in three different simulated intestinal fluids (pH 7.3) with phosphates (Sorensen's and Mc Ilvaine's buffers) and without phosphates (Tris-buffer). According to swelling studies and zinc ions release, it was showed that zinc ions keep adhering to the bead surface. Drug release and swelling behaviour from the two dosage forms depend not only on pH and ionic strength but also on the electrolytes there were in the dissolution medium. In calcium pectinate beads, rutin release was faster when phosphate buffers were used because precipitates (CaHPO4) were formed. This precipitate has a pumping effect on the calcium ions, destabilizing the gel structure and enhancing rutin release. In the case of zinc pectinate beads, two kinds of precipitate can be developed depending on the electrolytes composition. The development of Zn3(PO4)2 with a coating property reduced rutin release (Sorensen's buffer). On the other hand, development of ZnHPO4 has the pumping effect of zinc ions coming from the beads which increased rutin release (Mc Ilvaine's buffer).
Ali Assifaoui, Odile Chambin, Philippe Cayot, Carbohydrate Polymers 85 (2011) 388–393

B3058 – Combined effect of dynamic heat treatment and ionic strength on denaturation and aggregation of whey proteins – Part I

The aim was to investigate the effect of dynamic thermal treatment in a heat exchanger on the denaturation and aggregation of whey proteins. A 2% w/v WPI solution (pH 7.0), with or without NaCl addition (100 mM), was submitted to heat treatment at 100 °C. At low ionic strength, a nearly complete denaturation was observed, while the heat-treated samples at 100 mM ionic strength registered only 10% denaturation. It was shown that not only denaturation was reduced by the presence of NaCl, but also that the size of the aggregates formed during heat treatment was far smaller and remained essentially below 1 ?m. Surface tension measurements showed a faster adsorption and lower ? values for the non-polymerized proteins, whereas insoluble aggregates played only a poor role on the ? curves. Finally, experimental results demonstrated the strong interaction between ionic strength and dynamic thermal treatment on protein aggregation and properties.
I. Nicorescu, C. Loisel, C. Vial, A. Riaublanc, G. Djelveh, G. Cuvelier, J. Legrand, Food Research International 41 (2008) 707–713

B3057 – Formation and stability of amylose ligand complexes formed by high pressure treatment

Starch can be gelatinized during high pressure processing in the presence of water, but to a greater or lesser extent. Starch gelatinization is often accompanied by the formation of amylose complexes, in particular when a thermal treatment is used. Four different starches were considered in this study: potato, broad bean (Vicia faba), pea and tapioca. A comparison between high pressure-induced starch gelatinization (HPG) and conventional thermal gelatinization (TG) was made. In the case of broad bean starch, selected complexing molecules were considered for both thermal and high pressure treatments. Cross polarization/magic angle spinning (CP/MAS) 13C NMR, X-ray diffraction and thermal analysis were used to monitor physico-chemical changes in the structure and microstructure of starch preparations. Decanoic acid and carvacrol were selected as complexing agents to track the formation of amylose ligand complexes. It was observed that B-type starch (potato) was more resistant to pressure than the A-type starches (tapioca, broad bean and pea) considered in this study. The results showed that amylose ligand complexes were formed during high pressure treatment (20 min at 500 MPa at temperatures of 20 °C and 40 °C). Decanoic acid induced the complexing of amylose in the V6I type whatever the treatment used. On the other hand, the complexation of carvacrol appeared to depend on the temperature used during the high pressure treatment. It is assumed that carvacrol forms amorphous complexes with amylose during high pressure treatment. The amylose complexes were characterized by 13C CP/MAS NMR confirming the results obtained by X-ray analysis.
Patricia Le Bail , Benoît Chauvet, Hélène Simonin, Corinne Rondeau-Mouro, Bruno Pontoire, Marion de Carvalho, Alain Le-Bail, Innovative Food Science and Emerging Technologies, (2013)

B3056 – Aegle marmelos fruit pectin for food and pharmaceuticals: Physico-chemical, rheological and functional performance

Pectin is used in a number of foods as a gelling agent, thickener, texturizer, emulsifier and stabilizer. Bael fruit, obtained from Aegle marmelos, is a rich source of pectin. Bael fruit pectin (BFP) was extracted from ripe Bael fruits. The process yielded 15% (w/w) pure BFP. The swelling index decreased in the following order: water > pH 7.4 > pH 6.8 > pH 1.2 > HCl (0.1 N). Galacturonic acid content of 87.8%, degree of esterification of 47.2%, 17.3% methoxy groups, 0.29% acetyl groups and equivalent weight of 1209.5, indicate it to be a good gelling agent and easily amenable to derivatization. BFP exhibited a significant concentration-dependent prolongation of prothrombin time. The absence of hemagglutinating activity and antinutritional factors coupled with the activity to confer better emulsion capacity, stability and antimicrobial activity gives BFP a clear edge over commercial citrus pectin (CP) for exploitation as an additive in food and pharmaceuticals
Manish Jindal, Vineet Kumar, Vikas Rana, A.K. Tiwary, Carbohydrate Polymers 93 (2013) 386– 394

B3027 – Measurement and prediction of binary and trenary liquid-solid equilibria of pharmaceutical and food systems

Solid-liquid equilibria are imperatively required for any design calculations of equipments like crystallizers. Since any experimental measurement is not always easy to carry out, then the modeling of such data can be of a great importance. Consequently the present work deals with measurements by means of the differential scanning calorimetry (DSC) technique, and then predictions of solid-liquid equilibria in order to calculate the necessary interaction parameters for thermodynamic activity coefficient models like the UNIFAC or the NRTL. Binary and ternary systems which may have applications in the food or the pharmaceutical fields, were considered in the present study, with water or formamide as the solvents and D-Sorbitol, D-Glucose and D-Glucose monohydrate, as the solid solute
Bitchikh K, Meniai A-H, Louaer W, Energy Procedia 18 ( 2012 ) 1152 – 1164

B3024 – Denaturation and aggregation processes in thermal gelation of whey proteins resolved by differential scanning calorimetry

Gelation of globular proteins on heating involves two separate stages. The first is partial unfolding (denaturation) of the native globular structure; the second is intermolecular aggregation. Denaturation involves dissociation of intramolecular bonds (non-covalent and, in some cases, disulfide) and is therefore an endothermic process. The aggregation step involves formation of new bonds between protein molecules, and would therefore be expected to give a differential scanning calorimetry (DSC) exotherm on heating, but numerous previous studies of the thermal gelation of whey proteins, carried out on conventional (fast scanning) DSC calorimeters (typical sample mass 15–50 mg), have shown only endothermic transitions. In the present work, however, we have observed the endothermic (denaturation) and exothermic (aggregation) processes in thermogelation of whey protein isolate (WPI) as separate transitions in DSC heating traces recorded on a Setaram microcalorimeter (sample mass 850 mg). Under conditions where aggregation occurs much more slowly than denaturation (low protein concentration; low ionic strength) the two transitions are well resolved, with the exotherm from aggregation following the endotherm from denaturation. The position of the exotherm, however, appears to be time-dependent rather than temperature-dependent. On reduction in heating rate, the apparent peak-maximum temperature of the aggregation exotherm decreases towards the (essentially constant) position of the denaturation endotherm, and, at sufficiently low scan rates, the exotherm becomes obscured by the more intense endotherm. Progressive displacement of the exotherm into the temperature range of the denaturation endotherm also occurs in response to changes that accelerate intermolecular aggregation and accompanying gelation (addition of salt; increasing protein concentration). The absence of a detectable exotherm in previous studies using conventional calorimeters is attributed to the much smaller sample mass than in the Setaram instrument, giving much faster heat transfer, which may cause the exothermic heat flow from the slow aggregation process to be swamped by the endothermic heat flow from the more rapid denaturation process.
Sinead M. Fitzsimons, Daniel M. Mulvihill, Edwin R. Morris, Food Hydrocolloids 21 (2007) 638–644

B3023 – ‘‘Melt-in-the-mouth’’ gels from mixtures of xanthan and konjac glucomannan under acidic conditions: A rheological and calorimetric study of the mechanism of synergistic gelation

The effect of acidification on a typical commercial xanthan and on pyruvate-free xanthan (PFX), alone and in gelling mixtures with konjac glucomannan (KGM), has been studied by differential scanning calorimetry (DSC) and small-deformation oscillatory measurements of storage modulus (G') and loss modulus (G''). For both xanthan samples, progressive reduction in pH caused a progressive increase in temperature of the disorder–order transition in DSC, and a progressive reduction in gelation temperature with KGM. This inverse correlation is interpreted as showing that synergistic gelation involves disruption of the xanthan 5-fold helix, probably by attachment of KGM to the cellulosic backbone of the xanthan molecule (as proposed previously by a research group in the Institute of Food Research, Norwich, UK). Higher transition temperature accompanied by lower gelation temperature for PFX in comparison with commercial xanthan at neutral pH is explained in the same way. However, an additional postulate from the Norwich group, that attachment of KGM (or galactomannans) can occur only when the xanthan molecule is disordered, is inconsistent with the observation that gelation of acidified mixtures of KGM with PFX can occur at temperatures more than 60°C below completion of conformational ordering of the PFX component (as characterised by DSC). Increase in G' on cooling for mixtures of commercial xanthan with KGM at pH values of 4.5 and 4.25 occurred in two discrete steps, the first following the temperature-course observed for the same mixtures at neutral pH and the second occurring over the lower temperatures observed for mixtures of KGM with PFX at the same values of pH. These two ‘‘waves’’ of gel formation are attributed to interaction of KGM with, respectively, xanthan sequences that had retained a high content of pyruvate substituents, and sequences depleted in pyruvate by acid hydrolysis. At pH values of 4.0 and lower, gelation of mixtures of KGM with commercial xanthan followed essentially the same temperature-course as for mixtures with PFX, indicating extensive loss of pyruvate under these more strongly acidic conditions. Mixtures prepared at pH values in the range 4.0–3.5 gave comparable moduli at room temperature (20°C) to those obtained at neutral pH, but showed substantial softening on heating to body temperature, suggesting possible applications in replacement of gelatin in products where ‘‘melt-in-the-mouth’’ characteristics are important for acceptability to the consumer.
A.A. Agoub, A.M. Smith, P. Giannouli, R.K. Richardson, E.R. Morris, Carbohydrate Polymers 69 (2007) 713–724

B3022 – Preparation, authentication, rheology and conformation of theta carrageenan

Lambda carrageenan was extracted from hand-sorted tetrasporophytes of Gigartina skottsbergii. Theta carrageenan was prepared from it by treatment with alkaline borohydride. Infrared spectroscopy showed complete, or essentially complete, conversion of 4-linked residues to the 3,6-anhydride ring form, and no detectable contamination with gelling carrageenans (iota or kappa). Optical rotation and differential scanning calorimetry (DSC) showed no evidence of conformational transitions on cooling and heating. Solutions of theta carrageenan at 2.0 wt.% in water and in 0.1 M KCl were Newtonian at 20°C, and substantially less viscous than a 1.0 wt.% solution of the lambda carrageenan precursor. Close Cox–Merz superposition was observed between steady-shear (rotational) viscosity (?) and complex dynamic viscosity (?*) at equivalent values of shear rate ( ?/s 1) and frequency (?/rad s 1), and the variation of log G'' with log ? was linear, with a slope of 1.0, strongly indicating a solution of disordered coils. The absence of double-helix formation, and associated gelation, is explained by sulfation at O(2) of 3-linked residues. A previous report of gel formation by theta carrageenan is attributed to the presence of some gelling carrageenan in the lambda sample from which it was prepared.
Jonathan P. Doyle, Persephoni Giannouli, Brian Rudolph, Edwin R. Morris, Carbohydrate Polymers 80 (2010) 648–654

B2987 – Rehydration behaviour and ageing of dairy powders assessed by calorimetric measurements

On the basis of dissolution enthalpy measurements, the aims of this study were i) to investigate the feasibility of classifying the dissolvability of various dairy powders, and ii) to establish whether a change in rehydration behaviour that occurs with ageing could be predicted. No clear correlations could be established between the exothermic or endothermic nature of the calorimetric response and the rehydration ability of the powders studied. Dissolution enthalpy cannot thus be considered an absolute parameter that could be used to classify one dairy powder among others. On the contrary, it is experimentally shown that dissolution enthalpy is very sensitive both to the composition and the physical state of the powder. Consequently, dissolution enthalpy value can be considered as a marker representative of the manufacturing process and storage conditions. Evidence is made that following dissolution enthalpy over time could be a way to detect changes in powders due to ageing
Ousmane Sylla, Bruno Richard, Jean Francois Willart, Marc Descamps, Pierre Schuck, Guillaume Delaplace, Romain Jeantet, Innovative Food Science & Emerging Technologies Volume 14, April 2012, Pages 139–145

B2958 – Crystallisation behaviour of palm oil nanoemulsions carrying vitamin E

Four emulsions were prepared using high pressure homogenisation at 300 or 1200 bar and aqueous phases containing 4.5 wt% whey proteins in mixture with 20 wt% palm oil (PO), alone (E300 and E1200), or in which 20 wt% PO was replaced by vitamin (EV300, EV1200). Thermal behaviour of bulk fat and emulsions in the absence or presence of vitamin, as monitored by differential scanning calorimetry (DSC), indicated that fat crystallisation in supercooled melt was delayed in bulk fat in the presence of vitamin and more delayed in emulsions with lower droplet sizes and containing vitamin. These results were supported by (i) isothermal DSC experiments where exothermic peaks occurred at higher holding times and (ii) dynamic DSC experiments which showed lower melting reactions in emulsions with lower droplet sizes and containing vitamin. Synchrotron X-ray scattering measurements performed simultaneously at small and wide angles on fat samples stored at 4°C for 12 h showed coexistence of 2L and 3L longitudinal stacking in bulk fat without vitamin, and only 2L organisation of TAGs in the presence of vitamin. Trends in the proportions of ?, ?', ? lateral packing in lipid droplets were also observed to be more affected by the presence of vitamin rather than their size, indicating a higher rate of ? ? ?' ? ? polymorphic transformations in the presence of vitamin. Combining data obtained from DSC and X-Ray signals showed that lipid droplets with lower solid fat content, of which a higher proportion of b polymporphs, were those presenting lower size and lower ability for vitamin protection against chemical degradation, which is of great interest for formulation of lipid nanoparticles as bioactive matrix carriers.
Rizwan Shukat, Claudie Bourgaux, Perla Relkin, J Therm Anal Calorim (2012) 108, 153–161

B2923 – Studies on the impact of glycation on the denaturation of whey proteins

It could be shown for technologically relevant whey protein powders that denaturation of ?-lactoglobulin (?-Lg) is affected significantly by the extent of covalent modification of lysine residues by lactose. The amount of acid soluble ?-Lg as measured via RP-HPLC with UV detection after heating for 10 min at 80 °C increased from 40% (4.6% lysine modifcation) to 82% (22.4% lysine modification). An increase in glycation leads to a slower denaturation-induced oligomerisation, as shown by SDS-PAGE. Concomitant with an increase in lysine modification, the denaturation temperature increased from 79.5 to 84 °C, as measured by differential scanning calorimetry (DSC). Covalent attachment of lactose to whey proteins during preparation or storage significantly improves the heat stability of whey proteins, which may be of particular importance for the technological use of whey proteins varying in the degree of lysine modification
Bozena B. Mulsow, Mandy Jacob, Thomas Henle, Eur Food Res Technol (2009) 228, 643–649

B2916 – Physicochemical characteristics of inulins obtained from Jerusalem artichoke (Helianthus tuberosus L.)

The physicochemical characteristics (thermal stability, glass transition temperature and degree of crystallinity) of inulins, obtained from the tubers of four varieties Jerusalem artichoke (Helianthus tuberosus L.) grown in Bulgaria—Energina, Verona, Topstar and Spindel, were investigated. The inulins obtained had molecular weight from 4,882 to 5,600 Da (degree of polymerization around 30 fructose units). The experimental data from differential scanning calorimetry showed that the glass transition temperature of inulins is between 51 C and 55 C. It was found that the first transition (due to evaporation of the unbound water) starts from 77 to 80 C. The second transition phase started between 152 and 158 C, and it determines the limit of inulin thermal stability. The data from differential thermal analysis confirmed the results of differential scanning calorimetry with slight differences in the starting temperatures and durations of the phase transitions. X-ray analysis showed that the degree of crystallinity of inulins is very low (except for Spindel inulin—21%).
Ivan Panchev, Naiden Delchev, Daniela Kovacheva, Anton Slavov, Eur Food Res Technol (2011) 233, 889–896

B2887 – Osmo-dehydration of apple pulp studied by means of classical and Knudsen thermogravimetric approach

Classical thermogravimetry and its modification with Knudsen cells were employed to quantitatively investigate the osmo-dehydration of apple pulp samples. The data allowed realization of the complex mechanism of the process, which is not a mere solvent depletion, since it also implies sugar exchanges between the apple tissue and the hypertonic syrup used to dehydrate the fruit. The comparison between different hypertonic syrups, all at the same water activity, showed that maltose is more effective than either sucrose or a mixture of sugars that mimics the saccharide content of the apple. The conclusions are supported by a thermodynamic analysis of the aqueous solutions of these sugars at a concentration level as large as that of the hypertonic syrups used for the osmo-dehydration process.
Paola Pani, Marco Signorelli, Alberto Schiraldi, Danila Torreggiani, J Therm Anal Calorim (2010) 102, 383–390

B2844 – Imbibition, desiccation and mechanical deformations of zein pills in relation to their porosity

This paper deals with the interaction between zein (the main protein component of corn grain) and water. It induces macroscopic properties changes and may allow for the understanding of the basis of zein endosperm structure: vitreous endosperm is compact and floury endosperm is porous, giving the endosperm its hard and soft textures, respectively. In that aim porous pills made by compaction of zein powder submitted to different hydration/dehydration processes have been prepared and studied. In particular, imbibition measurements of a pure-water drop deposited onto a zein pill were performed. Also, desiccation of a zein pill previously imbibed induces strong mechanical stresses leading to crack formation and/or large deformations.
M.A. Sabino, L. Pauchard, C. Allain, P. Colonna, D. Lourdin, Eur. Phys. J. E 20, 29–36 (2006)

B2834 – Influence of freezing and of frozen storage on the specific heat capacity of trout and herring fillet

Effects of freezing and frozen storage on the specific heat capacity difference of native (not heat denatured) and heat denatured fillet ( ?dncP ) of trout and herring have been studied for the first time. Single and double freezing of fillet induced a clear reduction of the ?dncP of up to 15 mJ g?1 K?1 at each freezing step. Frozen storage at ?20 °C reduced the ?dncP of herring fillet but not of trout fillet. This is in agreement with the earlier detected instability of myosin transition temperature of herring and the stability of myosin transition temperature of trout [1]. The ?dncP is suggested as a new parameter for the evaluation of protein stability at freezing and frozen storage of fish. It has been shown, that a reversible endothermic effect between 2 and 22 °C in herring fillet is accompanied by a decrease of the storage modulus in the chopped fillet, which characterises the flexibility of the proteins. This mechanical change and the endothermic signal are missed in the chopped trout fillet at heating from 2 to 22 °C. This cold, reversible relaxation of fish proteins can be understood as a requirement for subsequent protein denaturation at frozen storage.
Michael Beyrer, Mark Rüsch gen. Klaas, European Food Research and Technology, January 2007, Volume 224, Issue 3, pp 349-353

B2833 – Differential thermal analysis, differential scanning calorimetry, and emulsions

This article is a review of some of the results we have obtained by studying various kinds of emulsions using techniques from the simplest one, a home-made differential thermal analysis to elaborated ones such as differential scanning calorimetry commercial devices. These techniques were used not only to determine energetic values but also essentially to show and quantify physical chemical phenomena such as undercooling, freezing, melting, mass transfer between droplets and solid formation involved in hydrate formation
Daniele Clausse, J Therm Anal Calorim (2010) 101,1071–1077

B2818 – The Influence of Concentration and Temperature on the Formation of !-Oryzanol+”-Sitosterol Tubules in Edible Oil Organogels

The gelation process of mixtures of ?-oryzanol and sitosterol structurants in sunflower oil was studied using light scattering, rheology, and micro-scanning calorimetry (Micro-DSC). The relation between temperature and the critical aggregation concentration (CAC) of tubule formation of ?-oryzanol and sitosterol was determined using these techniques. The temperature dependence of the CAC was used to estimate the binding energy and enthalpic and entropic contribution to the tubular formation process. The binding energy calculated at the corresponding temperatures and CACs were relatively low, in order of 2 RT (4.5 kJ mol?1), which is in accord with the reversibility of the tubular formation process. The formation of the tubules was associated with negative (exothermic) enthalpy change (?H0) compared with positive entropy term (?T ?S0 >0), indicating that the aggregation into tubules is an enthalpy-driven process. The oryzanol–sitosterol ratio affected the aggregation process; solutions with ratio of (60 oryzanol–40 sitosterol) started aggregation at higher temperature compared with other ratios.
Hassan Sawalha, Paul Venema, Arjen Bot, Eckhard Flöter, Erik van der Linden, Food Biophysics (2011) 6, 20–25

B2808 – Rheological and related study of gelation of xyloglucan in the presence of small molecules and other polysaccharides

Interaction between tamarind seed xyloglucan and the other polysaccharides, gellan gum or xanthan investigated by rheology, differential scanning calorimetry, and related methods was discussed. All these three polysaccharides do not form a gel at lower concentrations by itself at the experimental conditions studied but the gelation of xyloglucan occurs in the presence of gellan or xanthan. Gelation of xyloglucan in the presence of a polyphenol, epigallocatechin gallate, is also discussed. Hence the gelation of these mix- tures is caused by the synergistic interaction, and the models for the synergistic interaction were discussed. The gelation of polysaccharides by the synergistic interaction is of great value for food and related industries.
Katsuyoshi Nishinari, BoSook Kim, Yapeng Fang, Yoko Nitta, Makoto Takemasa, Cellulose (2006) 13, 365 –374

B2805 – Effects of alkaline-soluble okra gum on rheological and thermal properties of systems with wheat or corn starch

The effect of okra extract (OE) on the flowing and thermal properties of wheat and corn starch was investigated using rapid visco-analyzer (RVA), Brookfield viscometer, differential scanning calorimetry (DSC), and light microscopy. Starch-OE blends were prepared by replacing 5, 10, 15% of the starch. The RVA data showed that OE reduced the peak viscosity of both starches relative to the control. That was expected because of the reduction in the amount of starch that was replaced by OE. However, the drop in starch setback was more than just the omitted starch in the blend. The DSC scan data of the blends showed higher peak temperature compared to the control, indicating slower starch-granules gelatinization in the presence of OE. Brookfield profiles (performed at 50 !C) demonstrated increase in shear stress as a function of shear rate, but at high OE content, the shear stress of the blends showed resistant to change which was confirmed by lower slope of shear stress as a function of shear rate at higher OE content. Overall, it can be concluded that OE has influenced the investigated properties of the starches, either by indirectly controlling water movement, or by interacting with amylose as indicated by starchgel setback outcome.
Mohammed S. Alamri, Abdellatif A. Mohamed, Shahzad Hussain, Food Hydrocolloids 30 (2013) 541-551

B2804 – Effect of trimethylamine-N-oxide demethylase from lizardfish kidney on biochemical changes of haddock natural actomyosin stored at 4 and -10 °C

The addition of partially purified trimethylamine-N-oxide demethylase (TMAOase) from lizardfish kidney to haddock natural actomyosin (NAM) in the presence of cofactors (FeCl2, ascorbate, and cysteine) accelerated formaldehyde (FA) formation throughout the storage either at 4 or -10 °C (p < 0.05). 1H NMR spectroscopic study revealed that the formation of dimethylamine was enhanced with a concomitant decrease in trimethylamine oxide (TMAO) content when TMAOase was added, particularly at higher concentration. The loss of protein solubility increased as the result of FA formation, which was associated with the increased denaturation/aggregation of proteins. Lipid oxidation determined as hexanal content occurred during extended storage at different degrees. Generally, simulated systems without TMAOase and TMAO contained the highest hexanal content. Differential scanning calorimetry of NAM after storage at 4 and -10 °C for 15 days and for 8 weeks, respectively, showed the lower Tm and enthalpy of endothermic peaks corresponding to myosin and actin, suggesting the conformational changes induced by FA formed. Therefore, TMAOase exhibited the detrimental impact on haddock NAM, mainly caused by FA formation.
Kittima Leelapongwattana, Soottawat Benjakul, Wonnop Visessanguan, Nazlin K. Howell, Eur Food Res Technol (2008) 226,833–841

B2801 – Temperature and pH-sensitive chitosan hydrogels: DSC, rheological and swelling evidence of a volume phase transition

On heating, alkali chitin solutions undergo phase separation describing a characteristic “U-shaped” cloud point curve with a lower critical solution temperature (LCST) centered at ~30 °C. The process is accompanied by gelation of the polymer-rich phase. A different strategy to induce alkali chitin phase separation/gelation is by applying vacuum to the solution at room temperature during aprox. 72 h. Once washed to neutrality, chitin gels had a degree of acetylation of ~30-40 % (i.e. they were converted into chitosan). On cooling, these gels exhibit an exothermic peak in micro-DSC and a depression in G” and tan ! traces, evidencing a volume phase transition centered at ~20 °C. This transition is observed only within a narrow range of pH ~7.3 – 7.6. Variation in the mechanical response as a result of cyclic stepwise changes in temperature between 50 and 0 °C at pH values from 7.3-7.6, revealed that the G’ modulus of the gels increases on heating and decreases on cooling, a behavior that persists over at least four cycles of temperature change. Only marginal changes in G’ at pH 8.0 and not at all at pH 12.0 are observed. By contrast, the variation of G” persists throughout the range of pH. This behavior is rationalized in terms of the existence of a fine balance between hydrophobic and hydrophilic interactions at varying temperature and pH, thus effectively controlling swelling and shrinking states of the gel network. The degree of swelling at pH 7.6 reaches a minimum at ~22-25 °C.
F.M. Goycoolea, W.M. Argüelles-Monal, J. Lizardi, C. Peniche, A. Heras, G. Galed, E.I. Díaz, Polymer Bulletin 58, 225–234 (2007)

B2796 – The glass transition and crystallization of ball milled cellulose

Samples of ball milled cellulose were prepared by ball milling pulps from eucalyptus and softwood (spruce/pine). Water sorption isotherms were obtained by both dynamic vapor sorption and equilibration over saturated salt solutions, in the water content range of 5–42% db (db = dry basis; water as a % age of total solids). Dynamic mechanical analysis using a pocket technique showed a water content dependent thermal transition occurring at the same temperature for the two pulp samples, which was interpreted as a glass transition. Fitting the data to a Couchman–Karasz relationship predicted a value for Tg of the dry cellulose of approximately 478 K, which was similar to values previously reported for other dry polysaccharides. No clear glass transition could be observed calorimetrically, although an endotherm at approximately 333 K was measured, which in polymers is normally attributed to enthalpic relaxation, however the lack of dependence of this endotherm on water content suggests that the melting of some weak associations, such as residual hydrogen bonds, could be a more credible explanation. An exotherm was also observed on heating, which was dependent on water content and which was attributed to partial crystallization of the cellulose. This was confirmed by Wide angle X-ray diffraction and cross polarization magic angle spinning 13C NMR (CPMAS NMR). The recrystallisation was predominantly to form I of cellulose. This was thought to be caused by a small amount of residual form I (probably less than 5%) acting as a template for the crystallizing material. Differential scanning calorimetry reheat curves showed the appearance of freezable water for water contents higher than 20%, as a result of a transfer of water to the amorphous phase following crystallization. The increase in cellulose rigidity following crystallization was also confirmed by CPMAS NMR relaxation. Low resolution proton NMR T2 relaxation suggested the presence of proton water/cellulose exchange, which was active at water contents of 20% and above.
Sabrina S. Paes, Shaomin Sun, William MacNaughtan, Roger Ibbett, Johannes Ganster, Timothy J. Foster, John R. Mitchell, Cellulose (2010) 17, 693–709

B2693 – Examination of growth of probiotic microbes by an isoperibolic calorimetry

Due to the increasing consumers’ interest in up-to-date nutrition nowadays the production of main part of fermented dairy products (e.g. yogurt, kefir) is made by using probiotic microbes. The majority of this product group are the flavoured variations, the sweetener of which is, first of all, still refined sugar (e.g. saccharose). Honey of natural origin, consequently preferred from the nutritional physiological point of view, is suitable to replace this refined carbohydrate. In our experiments we have sweetened the most frequently used milk containing of 1.6 and 3.6% fat with generally used saccharose of 10%, and the difference in the dry material content was equilibrated by drink water of 3% (control product). The experimental product was sweetened with robinia honey of 13% (dry material content was 77%). The fermentation was performed with a probiotic culture of 5%, which was clinically tested to be probiotic. The fermentation process was conducted in isotherm regime at 36 C during 18 h in batch wessels using SETARAM Micro DSC II calorimeter. The calorimetric enthalpy was proportional to the probiotic microbe counts generated during the fermentation. Due to our experiments, we have come to the conclusion that honey instead of hindering much rather stimulates the growth of probiotic microbes. At sample pairs sweetened by saccharose and acacia honey, respectively, the higher enthalpy was measured at samples containing honey in all cases.
B. Schäffer, B. Keller, L. Daroczi, Denes Lorinczy, J Therm Anal Calorim (2010) 102, 9–12

B2555 – Freezing in non-acclimated oats. II: Thermal response and histology of recovery in gradual and rapidly frozen plants

Freezing in winter cereals is a complex phenomenon that can affect various plant tissues differently. To better understand how freezing affects specific tissue in the over wintering organ (crown) of winter cereal crops, non-acclimated oats (Avena sativa L.) were gradually frozen to ?3 °C and tissue damage during recovery was compared to plants that had been supercooled to ?3 °C and then frozen suddenly. Percentage of total water frozen, was the same whether crowns were frozen suddenly or gradually although the rate of freezing was considerably different. For example, all available water froze within 3 h in suddenly frozen crowns but it took more than 15 h for all available water to freeze in gradually frozen crowns. When plants were suddenly frozen, cells in the apical meristem were disrupted and apparently killed. In these plants re-growth was limited or non-existent. In contrast, the apical region of plants that were slowly frozen appeared undamaged but extensive vessel plugging was observed in cells of the lower crown, possibly from accumulation of phenolics or from microbial proliferation. These histological observations along with the calorimetric analysis suggested that the apical region was killed by intracellular freezing when frozen suddenly while the crown core was damaged by a process, which either induced production of putative phenolic compounds by the plant and/or permitted what appeared to be microbial proliferation in metaxylem vessels
David P. Livingston III, Shyamalrau P. Tallury, Thermochimica Acta, 481 (2009) 20-27

B2551 – Thermodynamic investigation of several natural polyols (II). Heat capacities and thermodynamic properties of sorbitol

The low-temperature heat capacity Cp,m of sorbitol was precisely measured in the temperature range from 80 to 390 K by means of a small sample automated adiabatic calorimeter. A solid–liquid phase transition was found at T=369.157 K from the experimental Cp–T curve. The dependence of heat capacity on the temperature was fitted to the following polynomial equations with least square method. In the temperature range of 80 to 355 K, Cp,m/J K–1 mol–1=170.17+157.75x+128.03x2–146.44x3–335.66x4+177.71x5 +306.15x6, x= [(T/K)–217.5]/137.5. In the temperature range of 375 to 390 K, Cp,m/J K–1 mol–1=518.13+3.2819x, x=[(T/K)–382.5]/7.5. The molar enthalpy and entropy of this transition were determined to be 30.35 0.15 kJ mol–1 and 82.22 0.41 J K–1 mol–1 respectively. The thermodynamic functions [HT–H298.15] and [ST–S298.15], were derived from the heat capacity data in the temperature range of 80 to 390 K with an interval of 5 K. DSC and TG measurements were performed to study the thermostability of the compound. The results were in agreement with those obtained from heat capacity measurements
B. Tong, Z. C. Tan, Q. Shi, Y. S. Li, S. X. Wang, Journal of Thermal Analysis and Calorimetry, Vol. 91 (2008) 2, 463–469

B2535 – Heterogeneous soft acid catalysis of the sucrose hydrolysis

Using a micro-calorimetrical DSC we have compared the acid-catalyzed inversion of sucrose in homogeneous and heterogeneous systems. Acetic acid was chosen as catalyst for homogeneous system, and several carboxylic cationites were used as heterogeneous catalysts. The kinetic apparent parameters (A, E, kap) for all the systems were calculated from DSC data with Friedmann’s method and catalytic constant, kcat 323, was further inferred. We found that the specific catalyst efficiency, qcat, in heterogeneous system is over 5000 times higher than in case of homogeneous ones. The activity of heterogeneous carboxylic systems is still about 30 times larger than those of a strong mineral acid in homogeneous catalysis. The results indicate the high efficiency of heterogeneous systems for soft acid catalysis of the sucrose hydrolysis
Dorina Chambre, Maria-Raluca Szabo, C. Popescu, Cornelia Idiïoiu, Journal of Thermal Analysis and Calorimetry, Vol. 94 (2008) 2, 417–420

B2525 – Comparative study of DSC pattern, colour and texture of shrimps during heating

Shrimp continues to be the most important commodity traded in value terms, accounting for 16.5% of the total value of internationally traded fishery products in 2004. Despite this importance of shrimp, literature is almost lacking on reports dealing with changes in functional properties and quality caused by heating shrimps while influence of freezing has been investigated more in depth. Therefore, objective of the study was cooking shrimp to different core temperatures in the range 30–80°C and monitoring changes in quality by measuring colour and texture attributes. DSC curves taken on differently heated shrimp differed markedly. With increasing temperature the enthalpy of denaturation decreased significantly.
R. Schubring, Journal of Thermal Analysis and Calorimetry, Vol. 95 (2009) 3, 749–757

B2461 – Calorimetric study of the native and postdenaturated structures in starches with different degree of hydration

DSC studies of melting process of annealed native structures and postdenatured ones in low-amylose starches with different degrees of hydration were carried out. The starch recrystallization at different thermal treatments of the samples was studied both after the complete and partial destroy of native structures. It has been shown that native structures as well as postdenatured ones possess the ability to perfection, which is most clearly seen at the annealing at temperatures inside their melting ranges. The results obtained demonstrate that at the same duration of annealing the process of crystal perfection for secondary starch structures proceed more intensively compared to the native ones. The presence of the remained native structures in partial melt in contrast to the remained gel ones restricts the ability of the recrystallized structures to perfection.
T. V. Belopolskaya, G. I. Tsereteli, N. A. Grunina, O. I. Smirnova, Journal of Thermal Analysis and Calorimetry, Vol. 92 (2008) 3, 677–682

B2385 – Isothermal calorimetry approach to evaluate shelf life of foods

Isothermal calorimetry (IC) traces were obtained at three temperatures for industrial whole-eggs, fresh milk and carrot convenience-salads to assess their durability when stored at various temperatures. According to the nature of the degradation process (microbial, metabolic (aerobic, or anaerobic), enzymatic), the order of magnitude of the exothermic signal recorded changed. The present work mainly aimed at determining the onset time of the calorimetric signal which was related to the stability (i.e. safe shelf life) of the food investigated. The higher the storage temperature, the earlier was the onset of thecalorimetric signal: the temperature effect on the stability time could be, therefore, determined. This piece of information was used to choose time±temperature±integrators suitable for the products considered. Stability times for the three products were also evaluated with other approaches (microbial plate counts, pH variation, development of turbidity). The comparison between the results of these traditional techniques and the calorimetric monitoring supported the reliability of the latter, which offers some peculiar advantages, like better temperature control, continuous follow up, easier mathematical description, overall energy balance of the degradation process.
Marco Riva, Dimitrios Fessas, Alberto Schiraldi, Thermochimica Acta 370 (2001) 73-81

B2343 – Morphology characterization of emulsions by differential scanning calorimetry

This article is a review of some results obtained by Differential Scanning Calorimetry (DSC) for characterizing the morphology of emulsions. In a classical DSC experiment, an emulsion sample is submitted to a regular cooling and heating cycle between temperatures that include freezing and melting of the dispersed droplets. By using the thermograms found in the literature for various emulsions, how to get information about the solidification and melting, the presence of solute, the emulsion type, the transfer of matter, the stability and the droplet size is shown.
D. Clausse, F. Gomez, I. Pezron, L. Komunjer, C. Dalmazzone, Advances in Colloid and Interface Science 117 (2005) 59 – 74

B2323 – Characterization of Myosin, Myoglobin, and Phospholipids Isolated from Pacific Sardine (Sadinops sagax)

Myoglobin (Mb) was extracted from Pacific sardine and added to Pacific whiting surimi to measure its effects on protein gelation. Biochemical and conformational changes of purified sardine myosin were investigated at various pHs. The greatest myosin protein solubility was observed at pH 7 and remained constant up to pH 11. Three endothermic peaks were obtained for samples prepared at pH 7 and 10, while no peaks were shown for pH 2 samples, indicating chemical denaturation of myosin occurred before thermal treatment. The greatest Ca2+-ATPase activity was observed at pH 7, while no activity was observed between pH 2-5 and pH 11. Total sulfhydryl content showed low activity at pH 2.5-4 while the greatest measure was obtained for samples at pH 5.5. Surface hydrophobicity was not detected from pH 2.5 to 5.0 because of low protein solubility, thereafter, the content remained consistent through pH 11.
Joo Dong Park, Ph.D. dissertation, Oregon State University, 2008

B2318 – Large enhancements in thermogelation of whey protein isolate by incorporation of very low concentrations of guar gum

The effect of the non-gelling polysaccharide guar gum on thermal gelation of whey protein isolate (WPI) was investigated by compression testing, oscillatory rheology and differential scanning calorimetry (DSC). All samples were prepared in 100mM NaCl, with the concentration of WPI held constant at 3.0 wt%. Under these conditions, DSC heating scans (Setaram microcalorimeter; sample mass E 850 mg; 1 1C/min) for WPI in the absence of guar gum showed an endothermic denaturation process with maximum heat flow at 76 1C and an exothermic aggregation process at 87 1C. On incorporation of increasing amounts of guar gum (0.0–0.5 wt%) the exotherm moved to progressively lower temperature, until eventually, at 0.5wt% guar gum, it was obscured by the more intense denaturation endotherm. This is attributed to segregative interactions (‘‘thermodynamic incompatibility’’) with guar gum promoting aggregation of thermally denatured whey protein. After heating to 80 1C and cooling to induce gelation of the whey protein, Young’s modulus (E) at 201C rose to a maximum at 0.05wt% added guar gum and decreased at higher concentrations, until at 0.5wt% guar gum the mixture was liquid-like. A similar initial increase and subsequent decrease with increasing concentration of guar gum was observed by oscillatory measurements (1 rad s 1; 0.5% strain) of storage modulus (G0), but the maximum occurred at 0.1wt% guar gum. The difference in optimum concentration is ascribed to use of a different time–temperature regime in preparing the samples for compression testing. The reduction in gel strength observed by both techniques at high concentrations of guar gum is attributed to excessive aggregation of WPI in response to segregative interactions, with consequent collapse of the crosslinked network. However, at the very low optimum concentration of 0.1wt% guar gum a large ( 12-fold) enhancement in gel strength (G0) was evident in comparison to WPI alone.
Sinead M. Fitzsimons, Daniel M. Mulvihill, Edwin R. Morris, Food Hydrocolloids 22 (2008) 576–586

B2317 – DSC measurements on sharks

Sharks are commonly termed fish, even though they are only distantly related to the classical (bony) fish. What differentiates a shark from a bony fish? Sharks have a spinal column and are thus vertebrates. However, their skeleton is not made of bones, but of cartilage, and together with their nearest relatives the rays and the chimeras they form the class of cartilaginous fish. Since the late 1980s trade in shark fin was considered to be one of the most valuable fishery products in the world. Another valuable shark product is cartilage. Shark meat has been used as food in coastal regions for over 5000 years. Small sharks are preferred for meat in many markets. In Germany, the belly flaps of spiny dogfish (Squalus acanthias) are smoked as “Schillerlocken”, an expensive gourmet item. The question came up to us recently if we were able to detect whether shark muscle were heat-treated as in the case of smoking or not. Different tariffs for heated and untreated fishery products make it important for processors to label their products correctly. According to customs departments this necessitates investigations into whether the declaration of goods is true or not. Looking at the relevant literature, papers dealing with thermal stability of shark muscle were very scarce. Therefore, we decided to perform DSC measurements on a variety of shark using a SETARAM MicroDSC VII and to compare the DSC patterns obtained. Beside thermal stability the colour of different shark meats were also measured instrumentally. To answer the question of whether DSC measurement can differentiate previously heat treated sharks from those lacking this treatment, the cutlets from smooth-hound (Mustelus spp.) underwent thermal treatment in the range from 40 to 70 ?C. DSC patterns of the shark muscle and the skin were used to observe the influence of heat treatment.
Reinhard Schubring, Thermochimica Acta 458 (2007) 124–131

B2303 – Comparison of curdlan and its carboxymethylated derivative by means of Rheology, DSC, and AFM

Abstract—Curdlan was carboxymethylated in an aqueous alkaline medium using monochloroacetic acid as the etherifying agent. The structure of carboxymethylated curdlan (CMc) was analyzed by FT-IR and NMR spectroscopy, which revealed that the carboxymethyl group was introduced mainly at the C-6 position as well as at the C-2 and C-4 positions. Furthermore, CMc was compared with the native curdlan by using rheology and DSC methods. It was found that in water, both polysaccharides behaved as pseudoplastic fluids and fit the power law and Herschel–Bulkley rheological models well. Both the storage shear modulus G0 and the loss shear modulus G00 of CMc aqueous solutions decreased and became more frequency dependent with decreasing concentration in comparison with the curdlan aqueous suspensions. The modulus–temperature curve also suggested that the gel characteristic of curdlan has been lost after chemical modification, which is consistent with the DSC results. AFM images revealed differences in the conformation of native and carboxymethylated curdlan, which changed from the aggregation of macromolecules to triple helices. All the experimental results suggest that the hydrogen bonds that bind curdlan with interstitial water to form the micelles have been destroyed completely and that the hydrophobic interactions related to the methylene groups at C-6 formed above 55 C disappeared due to the introduction of the hydrophilic carboxymethyl group.
Yang Jin, Hongbin Zhang,Yimei Yin and Katsuyoshi Nishinari, Carbohydrate Research 341 (2006) 90–99

B2288 – Effect of selective thermal denaturation of soybean proteins on soymilk viscosity and tofu’s physical properties

Thermal denaturation of soy proteins is a pre-requisite for tofu-gel formation. Differential scanning calorimetry of soymilk showed that the denaturation temperature of glycinin (92°C) is about 20°C higher than that of beta-conglycinin (71°C). This makes it possible to denature soybean proteins selectively using two-step heating, that is, soymilk was heated at 75°C for 5 min and then heated at 95°C for another 5 min. The effects of selective thermal denaturation (STD) on soymilk viscosity and tofu's physical properties were investigated with three soybean samples and varied soymilk solid contents (10-12%). Comparing to one-step heating (95°C, 5 min), STD increased soymilk viscosity by approximately 150% and tofu's apparent Young's modulus by approximately 20%, and reduced tofu's syneresis rate by approximately 10%. Change in tofu microstructure was also observed by scanning electronic microscopy. STD mechanism based on the interaction between glycinin and b-conglycinin was discussed.
Z-S. Liu, S.K.C. Chang, L-T. Li, E. Tatsumi, Food Research International 37 (2004) 815-822

B2251 – Determination of starch gelatinization temperature by ohmic heating

A method for measuring starch gelatinization temperature (T ), determined from a change in electrical conductivity (?), was developed. Suspensions of native starches with different starch/water mass ratios and pre-gelatinized starches were prepared, and ohmically heated with agitation to 90°C using 100 V by AC power at 50 Hz, and a voltage gradient of 10 V/cm. The results showed that ? of native starch suspensions was linear with temperature (R2 > 0.999) except for the gelatinization range, but the linear relationship was always present for the pre-gelatinized starch-water system. It was seen that the shape of d?/dT versus T curve was essentially similar to the endothermic peak on a DSC thermogram, and the gelatinization temperature could be conveniently determined from this curve. Thus, the segment profile on this curve was called the "block peak". The reason for the decrease in ? of native starch suspensions in the gelatinization range was probably that the area for motion of the charged particles was reduced by the swelling of starch granules during gelatinization.
F-D. Li, L-T. Li, Z. Li, E. Tatsumi, Journal of Food Engineering 62 (2004) 113-120

B2238 – Transport properties of a high porosity model food at above and sub-freezing temperatures. Part 1: Thermophysical properties and water activity

Few data are available on the thermophysical properties of high porosity foodstuff in the freezing domain. This paper presents some data obtained with a cellulose sponge used as a model food. The fraction of unfreezable water was obtained from differential scanning calorimetry data, using two different methods with a very good agreement. Water activity was experimentally determined at positive temperature. Experimental data were modeled by the Guggenheim-Anderson-de Boer (GAB) model, and a model deduced from the Clausius-Clapeyron equation. The GAB model was used to extrapolate these data in the subzero domain. It showed a good agreement until a water activity of 0.9, whereas the second model is usable only up to the value of 0.75.
N. Hamdami, J-Y. Monteau, A. Le Bail, Journal of Food Engineering 62 (2004) 373-383

B2226 – Effect of screw profile on residence time distribution and starch gelatinization of rice flour during single screw extrusion cooking

The effects of three types of screw elements, forward, mixing disc, and pin-mixing element, on residence time distributions of glutinous rice flour in a single screw extruder with different die opening areas have been investigated. Both mixing disc and pinmixing element yield longer residence time, higher specific mechanical energy (SME), and higher extrudate temperature compared with those for the forward screw element. The variation in die diameter did not significantly affect the mean residence time when the forward element was used. Nevertheless, increasing die diameter from 20 to 40 mm significantly reduced the mean residence time when mixing disc was used. Based on SME ranging from 3.6 to 20 kJ/kg, the extruder used in this study was classified as a low shear extruder. Due to the high moisture content (45%) and large die opening area, the die pressure was lower than 11.5 kPa. The utilization of mixing disc was found to raise the die pressure. The degree of starch gelatinization in extrudates was a function of the mean residence time. Three models were employed to fit the RTD data. The flow pattern in different screw profiles was discussed based on the model analysis.
G.Chao-Chi Chuang, An-I Yeh, Journal of Food Engineering 63 (2004) 21-31

B2213 – Single-phase mixed gels of xyloglucan and gellan

Gelation in mixtures of xyloglucan and gellan was investigated using dynamic rheometry, differential scanning calorimetry (DSC), and atomic force microscopy (AFM). The examined gellan and xyloglucan did not form a gel at concentrations below 0.5% w/w and 0.75% w/w, respectively, while a mixture of 0.05% w/w gellan and 0.7% w/w xyloglucan formed a single-phase gel, demonstrating synergistic interactions between gellan and xyloglucan. The coil-to-helix transition temperature of gellan alone, determined by DSC, increased with increasing gellan concentration. In the case of binary polysaccharide mixtures, the conformational transition temperature of gellan increased with increasing xyloglucan content at a total polysaccharide concentration of 0.75% w/w. AFM images of mixtures diluted from 0.05% w/w gellan and 0.7% w/w xyloglucan revealed network structures of gellan at the micrometer scale. These results suggest that xyloglucan increases the effective concentration of gellan in a mixture, presumably via volume exclusion effects, and thus a network of gellan is formed even at concentrations much lower than the gelation threshold of gellan alone.
S. Ikeda, Y. Nitta, B.S. Kim, T. Temsiripong, R. Pongsawatmanit, K. Nishinari, Food Hydrocolloids 18 (2004) 669-675

B2204 – Thermophysical properties evolution of French partly baked bread during freezing

Few data are available on the thermophysical properties of the frozen partly baked breads. In this paper, thermophysical properties, including apparent and true densities, specific heat, enthalpy and effective thermal conductivity were determined separately for crumb and crust of partly baked bread. Total enthalpy of fusion, unfrozen water and solid specific heat were determined by differential scanning calorimetry. The apparent specific heats were estimated in base of the unfrozen water at -40°C and initial freezing point. The effective thermal conductivity was measured with a line source probe in the range -35 to 25°C. Four predictive models of the effective thermal conductivity of porous food were developed (parallel, series, Krischer and Maxwell models). The effective thermal conductivity predicted by Krischer model was in good agreement with the experimental data.
N. Hamdami, J-Y. Monteau, A. Le Bail, Food Research International 37 (2004) 703-713

B2187 – NMR investigations of the 4-ethyl guaicol self-diffusion in iota (i)-carrageenan gels

Self-diffusion coefficient of an aroma molecule (4-ethyl guaicol) was measured using the pulsed field gradient spin echo NMR (PGSENMR) method in order to investigate the influence of a macromolecular matrix on its diffusion and release processes. Iota (i)-carrageenan was used for its ability to form thermoreversible gels in aqueous salt solutions. Variations of the i-carrageenan and the salt concentrations permitted various gels with different thermal and rheological properties to be obtained. These latter were modified by an isotope effect obtained by preparing gels in D2O. The NMR self-diffusion measurements realised for water and the aroma molecules indicated neither chemical interactions with i-carrageenan, nor obstruction effects from the polysaccharide chains. In i-carrageenan gels, the diffusional phenomenon was highly dependent on the heterogeneous gel structure and controlled by hydrodynamic interactions due to frictional drag between each molecule of the system and water microviscosity changes.
C. Rondeau-Mouro, A. Zykwinska, S. Durand, J-L. Doublier, A. Buléon, Carbohydrate Polymers 57 (2004) 459-468

B2175 – Role of cosolutes in gelation of high-methoxy pectin. Part 1. Comparison of sugars and polyols

Mixtures of high-methoxy pectin (DE 70; 1.0 wt%; pH 3.0) with ethan-1,2-diol, glycerol, xylitol, sorbitol, glucose, fructose or sucrose at concentrations of 50, 55, 60 and 65 wt% were prepared at 95°C and changes in storage modulus (G') and loss modulus (G") during cooling to 5°C, heating to 90°C and re-cooling to 5°C (at 1°C/min) were measured at 1 rad s-1 and 0.5% strain. In all cases, the onset temperature for gelation during cooling and the moduli recorded at 5°C increased with increasing concentration of cosolute. Both values, however, were substantially lower for the liquid cosolutes (ethan-1,2-diol and glycerol) than for mixtures incorporating the same concentrations of the solid cosolutes. The difference is attributed to inhibition of pectin-pectin interactions by pectin-cosolute interactions, which in turn are inhibited by cosolute-cosolute interactions, these being weaker for the liquid cosolutes than for the solids (as indicated by lower melting points). On heating, there was an initial reduction in modulus, with the same temperature-course as the increase on cooling; for the solid cosolutes, this was followed by an increase attributable to hydrophobic association of methyl ester substituents. No such increase was seen with the liquid cosolutes, but differential scanning calorimetry studies showed two (reversible) thermal transitions in all cases, one over the temperature-range of the initial gelation process on cooling and the other coincident with the increase in modulus on heating in the presence of the solid cosolutes. The absence of any detectable increase in modulus on heating with the liquid cosolutes is attributed to accumulation of cosolute around the polymer chains (i.e. pectin-cosolute interactions) promoting hydrophobic association between methyl ester groups on the same chain, or within small clusters of chains, with, therefore, no contribution to network structure. At high concentrations of the solid cosolutes, the increase in modulus on heating was followed by a decrease at higher temperature; this is attributed to excessive aggregation, and was reflected in lower moduli on subsequent re-cooling to 5°C, in contrast to the enhancement in gel strength after heating and cooling that was observed at lower concentrations of the same cosolutes.
A. Tsoga, R.K. Richardson, E.R. Morris, Food Hydrocolloids 18 (2004) 907-919

B2171 – The effect of the linear charge density of carrageenan on the ion binding investigated by differential scanning calorimetry, dc conductivity, and kHz dielectric relaxation

The effect of the linear charge density of natural polyelectrolyte, carrageenan, on the ion binding to carrageenan molecules in relation to the gelation was investigated by using the dielectric relaxation spectroscopy, dc conductivity, optical rotation, and differential scanning calorimetry (DSC). Although carrageenan is an anionic polysaccharide, carrageenan molecules in the helix state at low temperatures can bind not only cation, such as potassium and cesium, but also anion, such as iodide. The dc conductivity steeply decreases just below the coil-helix transition temperature, which indicates the binding of ion to the carrageenan molecules in the helix state due to the increase of the linear charge density compared with that in the coil state. The addition of NaI promotes the helix formation, and prevents from aggregation of helices, which was suggested by the results of the dynamic shear modulus and the DSC, and resulted in an increase of the relaxation amplitude of the lowest frequency relaxation (~kHz) attributed to the fluctuation of the tightly bound counter ions along the high charge density region (helix). It is concluded that binding of iodide induces (1) the increase in the amount of tightly bound counterions to carrageenan molecules and (2) the formation of non-aggregated helix.
M. Takemasa, K. Nishinari, Colloids and Surfaces B: Biointerfaces 38 (2004) 231-240

B2152 – Thermoreversible gelation and phase separation in aqueous methyl cellulose solutions

We derived typical phase diagrams for aqueous solutions of methyl cellulose (MC) of different molecular weights via micro-differential scanning calorimetry, small-angle X-ray scattering, and visual inspection. The phase diagrams showed the cooccurrence of gelation and phase separation and qualitatively agreed with the theoretically calculated diagrams. The sol-gel transition line and phase separation line of a lower critical solution point type shifted toward lower temperatures and lower concentrations with an increase in theMCmolecular weight. The sol-gel transition line intersected at a temperature higher than the critical point of the phase separation; therefore, both sol-gel phase separation and gel-gel phase separation were possible, depending on the temperature. Specifically, through visual inspection of a high molecular weight MC sample in the critical temperature region, we observed phase separation into two coexisting gels with different polymer concentrations.
M. Takahashi, M. Shimazaki, J. Yamamoto, Journal of Polymer Science: Part B: Polymer Physics 39 (2001) 91-100

B2151 – Gel-sol transition of methylcellulose

The gelation mechanism of aqueous solutions of methylcellulose (MC) with different molecular weights was studied by small deformation oscillation rheological measurments and differential scanning calorimetry (DSC). The gelation is promoted by the increase in molecular weight of MC: the elastic modulus becomes larger, the gelation occurs at lower temperatures and the DSC peaks accompanying the gel-sol transition become sharper. Cooling DSC curves split into two peaks, indicating that the gel-to-sol transition occurred via two steps.
K. Nishinari, K.E. Hofmann, H. Moritaka, K. Kohyama, N. Nishinari, Macromolecular Chemistry and Physics 198 (1997) 1217-1226

B2147 – Development of a DSC method for determination of certain technological parameters of margarine and mixed-fat spread

Nutritional-physiological research of near past decades had established the real nutritional value of fats and oils. In the former theory the nutritional value of fats and oils is influenced mainly by the rate of saturated/unsaturated fats. It was ruled out, and positive, inert or risk physiological effect of every single fatty acid had been established. The health-care effect of omega-3 fatty acid mainly by the favourable (<3:1) rate of omega-6/omega-3 was established, as inert was concerned the saturated C16 fatty acid and the maximal amount of trans-fatty acids carrying health risk in fats was legally regulated in some countries. These nutritional-physiological requirements were mainly fulfilled by margarine producers and the elementary fats were selected in such a way that they should meet these requirements. Our method helps to the producers to quickly determine the amount of the liquid and solid fat at certain temperature and/or to adjust the technological temperature parameters. The main steps of our method are: a./ determination of cooling rate (K min-1) of the crystallizer device; b./ determination of the rate of liquid/solid fat at 10°C temperature. This value is used for the determination of the rate of fats and oils as a function of technology and required consistency firmness (spread ability); c./ determination of the temperature from the cooling curve where the crystallization of most part of the fat has finished. This value is used for the determination of outlet temperature parameter of product coming out from the crystallizer device for margarines or mixed-fat spreads with water-in-oil system.
D. Lörinczy, G. Regdon Jr., B. Keller, S. Szakaly and B. Schäffer, Journal of Thermal Analysis and Calorimetry 88 (2007) 351-354

B2144 – Insights for optimizing dissolution of food powders

A. Marabi, G. Mayor, A. Burbidge, R. Wallach, I.S. Saguy, A. Raemy, 38e Journées de Calorimétrie et d'Analyse Thermique - Montpellier (2007) 31-32

B2139 – A molecular description of the gelation mechanism of curdlan

The gelation of aqueous suspensions of the polysaccharide curdlan has been studied by dynamic rheological measurements, differential scanning calorimetry, and low-resolution time-domain 1H-NMR. Gel formation from several samples, each originating from a curdlan fraction of differing molecular weight, has been observed in order to further clarify the nature of observed phenomena by monitoring their dependence on degree of polymerisation. The results from the complementary techniques described here, in addition to those in existing literature, both for curdlan and for other beta-(1,3) glucans, have been used to build up a consistent framework for the interpretation of results. Broadly, this involves the plasticisation and dissolution of dried material on heating, the time-dependent annealing of native (as biosynthesised) structures, and the trapping of imperfectly formed pseudo-equilibrium states on re-cooling, in concert with the creation of microfibrils and network formation.
H. Zhang, K. Nishinari, M.A.K. Williams, T.J. Foster, I.T. Norton, International Journal of Biological Macromolecules 30 (2002) 7-16

B2138 – Thermal measurements of curdlan in aqueous suspension during gelation

Differential scanning calorimetry (DSC) measurements of curdlan in aqueous suspension were carried out in a temperature range of 40- 200°C by using silver pans with and without heat treatment, respectively. Silver pans with heat treatment were heated at 200°C and then cooled. Heating DSC curves of curdlan in aqueous suspension showed an endothermic peak around 60°C and were identical below 120°C, but quite different above 120°C. A large exothermic peak was observed at 140-190°C in a heating DSC curve when a non-heated pan was used, whereas a small endothermic peak was observed at 140-160°C and no exothermic peak was observed at higher temperatures when a heated pan was used. It was suggested that the large exothermic peak was attributed to an interaction between the non-heated silver pan and water above 120°C. Only the endothermic peak at 140-160°C reflected the reality of the thermal property of curdlan in aqueous suspension, which was caused by the melting of the curdlan gel formed.
H. Zhang, L. Huang, K. Nishinari, M. Watase, A. Konno, Food Hydrocolloids 14 (2000) 121-124

B2128 – Changes of hen eggs and their components caused by non-thermal pasteurizing treatments II. Some non-microbiological effects of gamma irradiation or hydrostatic pressure processing on liquid egg white and egg yolk

Experiments were performed to study changes caused by irradiation or high hydrostatic pressure pasteurization of liquid egg white by differential scanning calorimetry, spectrofluorimetry, electronic nose measurements and NIR-spectrometry. The non-thermal pasteurization treatments were also assessed in relation to loss of carotenoid content, and lipid- and cholesterol oxidation of liquid egg yolk. Unlike radiation pasteurization, high pressure processing caused protein denaturation in egg white, which manifested in changes of its DSC-thermogram and intrinsic tryptophan fluorescence. Electronic nose testing showed changes of the head-space volatile composition of egg albumen, particularly as a function of radiation treatment. Both treatments caused changes in the NIR-spectrometric "fingerprint" of the liquid egg white. Various chemometric analyses of the results of the latter instrumental methods, particularly statistical techniques developed by the group of one of the co-authors of this article, demonstrated the potential for detection and characterization of the applied non-thermal processing techniques on liquid egg white. Irradiation induced more carotenoid degradation and lipid oxidation in liquid egg yolk than pressure processing.
E. Andrassy, J. Farkas, Zs. Seregély, I. Dalmadi, E. Tuboly and V. Lebovics, Acta Alimentaria 35 (2006) 305-318

B2115 – Effect of hydrothermal treatment on the physical and rheological properties of maize starches

Standard maize (SMS) and waxy maize starch (WMS) were hydrothermally treated at their residual moisture level ( ~12%) by Instantaneous Controlled Pressure Drop process in order to obtain pre-gelatinised starches in a single step. The effects of two parameters of this process, namely the steam pressure level and processing time, on the structural and rheological properties of the native maize starches were described. The occurrence of partial gelatinization for DIC treated starches was clearly attested by the increase of the median volume diameter in cold water, the decrease of the gelatinization enthalpy and a loss of birefringence under polarized light. This was more prominent for the highest pressure and longest time: 2.7-3 bar for 200-300 s. Sensitivity of starches to the process was also dependent on their origin, SMS being more affected than WMS.
C. Loisel, Z. Maache-Rezzoug, C. Esneault, J.L. Doublier, Journal of Food Engineering 73 (2006) 45-54

B2113 – Structure and rheological properties of acid-induced egg white protein gels

This study compares the rheological properties of acid-induced gels prepared of industrial spray-dried egg white proteins (EWP) with the acid-induced gels prepared of ovalbumin (OA) and whey protein isolate (WPI). Also we aimed to form transparent gels of EWP by means of the cold-gelation process. We showed that it was not possible to prepare cold-set gels because ovotransferrin (OT), present in EWP, was found to interfere with fibril formation. Therefore, we developed a new purification method in which first OT was selectively denatured by a heating step, subsequently precipitated by acidification and removed by centrifugation. Finally, the supernatant was desalted by ultra filtration. This resulted in a preheated EWP preparation, which mainly contains OA (>80%). By removing OT using this new preheat procedure transparent gels were obtained after acid-induced gelation. Fracture properties of various EWP preparations were determined and compared with those of acid-induced gels of OA and WPI. Gels formed from different EWP preparations were weak (fracture stress 1-15 kPa, fracture strain 0.3-0.7), and the networks consisted of thin strands with hardly any additional disulphide bonds formed during the gelation step. In conclusion, the microstructure of the aggregates formed in the first step of the cold-gelation process and the amount of additional disulphide bonds formed during the second step appeared to be the determining factors contributing to the hardness and deformability of acid-induced gels of egg white proteins.
M. Weijers, F. van de Velde, A. Stijnman, A. van de Pijpekamp, R.W. Visschers, Food Hydrocolloids 20 (2006) 146-159

B2112 – Gamma irradiation of cowpea (Vigna unguiculata L. Walp) flours and pastes: Effects on functional, thermal and molecular properties of isolated proteins

In a previous study irradiation of cowpea flours and pastes at medium (10 kGy) and high (50 kGy) doses resulted in significant changes in protein-related functional properties. To understand some of the effects of gamma irradiation on cowpea proteins in particular, we isolated proteins from cowpea flours (FPC) and pastes (PPC) treated with gamma irradiation at 2, 10, and 50 kGy and analyzed their functional, thermal and molecular properties. Nitrogen solubility index of both FPC and PPC decreased, whereas oil absorption and emulsion capacities increased significantly with increasing irradiation dose. Differential scanning calorimetry showed decreases in transition temperatures (Td) and enthalpies (?H), indicating a progressive denaturation of cowpea proteins with increasing irradiation. Size exclusion HPLC revealed increases in protein molecular weights, probably due to protein-protein cross-linking with irradiation in a dose-dependent manner. Reducing SDS-PAGE of FPC and PPC samples seems to suggest that the contribution of disulphide bonds to irradiation-induced cowpea protein-protein cross-linking is small.
J.O. Abu, K. Müller, K.G. Duodu, A. Minnaar, Food Chemistry 95 (2006) 138-147

B2109 – High pressure-low temperature processing of food proteins

High pressure-low temperature (HP-LT) processing is of interest in the food field in view of: (i) obtaining a "cold" pasteurisation effect, the level of microbial inactivation being higher after pressurisation at low or sub-zero than at ambient temperature; (ii) limiting the negative impact of atmospheric pressure freezing on food structures. The specific effects of freezing by fast pressure release on the formation of ice I crystals have been investigated on oil in water emulsions stabilized by proteins, and protein gels, showing the formation of a high number of small ice nuclei compared to the long needle-shaped crystals obtained by conventional freezing at 0.1 MPa. It was therefore of interest to study the effects of HP- LT processing on unfolding or dissociation/aggregation phenomena in food proteins, in view of minimizing or controlling structural changes and aggregation reactions, and/or of improving protein functional properties. In the present studies, the effects of HP-LT have been investigated on protein models such as (i) beta-lactoglobulin, i.e., a whey protein with a well known 3-D structure, and (ii) casein micelles, i.e., the main milk protein components, the supramolecular structure of which is not fully elucidated. The effects of HP-LT processing was studied up to 300 MPa at low or sub-zero temperatures and after pressure release, or up to 200 MPa by UV spectroscopy under pressure, allowing to follow reversible structural changes. Pressurisation of ~2% beta-lactoglobulin solutions up to 300 MPa at low/subzero temperatures minimizes aggregation reactions, as measured after pressure release. In parallel, such low temperature treatments enhanced the size reduction of casein micelles.
E. Dumay, L. Picart, S. Regnault, M. Thiebaud, Biochimica et Biophysica Acta 1764 (2006) 599-618

B2098 – Functional properties of whey proteins as affected by dynamic high-pressure treatment

An ultra high-pressure homogenizer was used to treat whey protein isolate solutions (3%, w/w). The treated solutions (up to 300 MPa) were characterised for both physico-chemical properties (particle size distribution, surface hydrophobicity and structural conformation) and functional properties (solubility, foaming stability and interfacial rheology). Dynamic high-pressure treatment did not affect the conformation of the proteins (determined by micro-calorimetry, size-exclusion chromatography and electrophoretic technique). This treatment dissociated large protein aggregates leading to unmasking of the buried hydrophobic groups without affecting protein solubility. Interactions may then occur between these groups that enhance the viscoelasticity of airwater interfaces (assessed by drop tensiometry) and improve foam stability (evaluated by sparging method). Dynamic high-pressuretreated whey proteins showed better foaming and stabilising properties.
H. Bouaouina, A. Desrumaux, C. Loisel, J. Legrand, International Dairy Journal 16 (2006) 275-284

B2097 – Effect of gamma-irradiation on some physicochemical and thermal properties of cowpea (Vigna unguiculata L. Walp) starch

Previously, we reported that starch-related functional properties of cowpea flours and pastes were modified by 2, 10 and 50 kGy gamma-irradiation doses. To elucidate some of the effects of gamma-irradiation specifically on cowpea starch as well as the actual contribution of starch to the observed functional modifications at the flour and paste level, starch was isolated from irradiated cowpea flours and pastes and studied using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), Fourier Transform Infra-Red (FTIR) spectroscopy, Rapid Visco-Analyser (RVA) pasting properties, and some functional properties. Pasting (peak, trough, breakdown, final, and setback viscosities) and swelling properties were significantly decreased in a dose-dependent manner. DSC of cowpea starch showed increases in peak gelatinisation temperature with increasing irradiation dose. SEM (2500x) microphotographs showed that up to 50 kGy irradiation did not present any visible physical effect on the cowpea starch granule. FTIR indicated that starch granule surface order (crystallinity) was not affected by the irradiation doses employed.
J.O. Abu, K.G. Duodu, A. Minnaar, Food Chemistry 95 (2006) 386-393

B2075 – Measurement of cation binding to immobilized vanillin by isothermal calorimetry

Isothermal calorimetry was used to determine enthalpy changes for interaction of divalent cobalt, nickel, copper, and zinc chlorides with silica gel functionalized with vanillin, Sil-Van. The thermal effect, Qint, and the corresponding amount of cation that interacts, nint, were obtained in the same experiment. Langmuir expressions for adsorption isotherms were applied to determine the maximum adsorption capacity to form a monolayer, Nmon, and the energy of interaction for a saturated monolayer per gram of Sil-Van, Qmon. From knowledge of Nmon and Qmon, themolar enthalpy of interaction for formation of a monolayer of anchored cations per gram of Sil-Van, ?monHm, was determined. Interactions between the Lewis-acidic cations and the donor atom attached to silica are reflected by ?monHm values in the order Ni2+ > Cu2+ > Zn2+ ~ Co2+.
E.F.S. Vieira, A.R. Cestari, E.B. de Santos, C.X. Rezende, Journal of Colloid and Interface Science 298 (2006) 74-78

B2073 – Formation of amylose complexes with C6-aroma compounds in starch dispersions and its impact on retention

Interactions between aroma compounds and starch matrices may increase the retention of aroma compounds. In particular, the linear amylose of starch, is able to form inclusion complexes with a wide variety of flavour compounds. The retention of four C6 aroma compounds (hexanol, hexanal, trans-2-hexenal and 2-hexanone) in model starch dispersions was measured using the exponential dilution method. The complexing behaviour of these aroma compounds with amylose and two starch dispersions was studied by differential scanning calorimetry (DSC) and X-ray diffraction, to determine the relative importance of this factor. The ability of hexanol and hexanal to induce a specific interaction with amylose is showed by both methods. This can explain their high retention in model starch dispersions. In contrast, the inability of 2-hexanone to interact with amylose explained its low level of retention.
C. Jouquand, V. Ducruet, P. Le Bail, Food Chemistry 96 (2006) 461-470

B2055 – Fish gelatin: Structure, gelling properties and interaction with egg albumen proteins

Gelatin was obtained from the skin of North Sea horse mackerel (Trachurus trachurus), using sodium hydrogen carbonate (0.125%), sodium hydroxide (0.2%), sulphuric acid (0.2%), and citric acid (0.715%) in distilled water, followed by filtration, deionisation. The proximate composition of the extracted fish skin gelatin indicated that the ash, moisture, colour, weight average molecular weight (195.8 kDa), Bloom (230) and pH (6.0) compared well commercial gelatin. The imino acid and hydrophobic amino acids profile of extracted horse mackerel gelatin were closer to those of the commercial warm water tilapia gelatin rather than the non-gelling cod gelatin. FT-Raman spectroscopy confirmed that hydrophobic groups (tyrosine doublet ratio 850/830 cm-1 and CH stretch region) as well as alpha-helix and random coil, for horse mackerel gelatin were in between those of tilapia and cod gelatin. In addition, large and small deformation rheological and thermodynamic properties were investigated for horse mackerel gelatin in isolation and in combination with egg albumen (egg white) protein. A mixture of gelatin:egg albumen (3:10) gave greater G' valuesthan expected. Both differential scanning calorimetry and microscopy supported interaction between gelatin and egg albumen proteins. The gelling properties and compatibility with egg proteins makes the horse mackerel gelatin a potential replacer of porcine and bovine gelatins in desserts and bakery products.
F. Badii, N.K. Howell, Food Hydrocolloids 20 (2006) 630-640

B2052 – Consolidation of foams deriving from emulsions by temperature cycling (“tempering”)

We produce oil-in-water emulsions comprising almost totally crystallized droplets at T=4°C, stabilized by a mixture of proteins and low molecular weight surfactants. Foams are produced by incorporating air bubbles in the previous emulsions under intense stirring at low temperature (whipping process). The kinetic stability of the foams can be substantially enhanced by warming the systems immediately after whipping, and cooling them again. Owing to this treatment referred as temperature cycling or "tempering", foams clearly stiffen and they can then be stored at 4°C for several weeks without any visible structural change. In this paper, we investigate the origin of this consolidation.We follow the bulk rheological properties of foams during and after the tempering treatment. The storage modulus, G', is significantly larger than the loss modulus, G" , reflecting the essentially elastic nature of the materials. G' exhibits a dramatic increase when tempering is applied. The elasticity in whipped emulsions arises from the network of interconnected solid fat droplets. By using different techniques (differential scanning calorimetry (DSC), NMR, light scattering), we deduce that an increase of the network connectivity due to partial coalescence is the most probable cause for the elasticity and stabilisation gains obtained after tempering.
E. Gravier, N. Drelon, L. Boisserie, A. Omari, F. Leal-Calderon, Colloids and Surfaces A: Physicochem. Eng. Aspects 282-283 (2006) 360-368

B2042 – Structural, thermal and viscoelastic characteristics of starches separated from normal, sugary and waxy maize

Starches separated from five types of maize (two normal, one sugary and two waxy) were investigated for physicochemical, thermal, amylopectin structure and viscoelastic properties. Kisan and Paras were normal maize while Parbhat and LM-6 were waxy maize type. Apparent amylose content of normal and sugary maize was 29.5-32.6 and 41.0%, respectively. Swelling power of normal, sugary and waxy maize starches was 11.6-15.2, 7.8 and 30.2-39.2 (g/g), respectively. X-ray diffraction of maize starches indicated typical A-pattern. Maize starch showed a single broad peak at 2?=23.2° and a dual peak 2?=17°-18.1, respectively. Waxy maize starches showed the presence of greater crystallinity than other starches while sugary maize starch showed the presence of lower crystallinity and a large amount of amylose-lipid complex. Intrinsic viscosity [?] of starches in 90% DMSO at 25°C was 79.7-119.5 ml g-1 for normal, 70.5 ml g-1 for sugary and 107.2-118.1 ml g-1 for waxy starches. Branch chain-length distribution of amylopectin revealed that the apparent amylose, long side chain- and short side chain-amylopectin proportion ranged between 0.0-41%, 13.4-31.5% and 41.5-66.8%, respectively, among the various maize starches. Maize sugary showed the highest apparent amylose content and the least amount of short- and long-side chains of amylopectin. LM-6 and Parbhat showed higher proportion of both longand short-chain amylopectin as compared to other starches. Distribution of alpha-1, 4-chains of amylopectin (short-/long-chain) ranged between 2.1 and 3.4, the least for LM-6 and the highest for Paras starch. The transition temperatures (To-Tc) ranged between 60.5 and 76.1°C for sugary, 63.5-76.3°C for normal and 64.4-81.3°C for waxy maize starch. The enthalpy of gelatinization (?Hgel) of sugary, normal and waxy maize starches was 2.47, 3.7-4.75 and 4.15-5.4 J/g, respectively. Normal and sugary maize starches showed higher G' and G'' than waxy type starches. The change in the moduli during cooling and reheating of pastes cooked at different temperatures revealed low disintegration of granular structure in starch with higher amylose and amylose-lipid complex as well as low crystallinity. The changes in moduli during 10 h at 10°C revealed highest retrogradation in maize sugary followed by Paras and Kisan starch.
N. Singh, N. Inouchi, K. Nishinari, Food Hydrocolloids 20 (2006) 923-935

B2040 – Mechanical behaviour of corn flour and starch-zein based materials in the glassy state: A matrix-particle interpretation

Starch-zein systems were characterised by their dynamic mechanical behavior. Although the main relaxation temperatures were located in the same range of temperature for the various zein contents, significant differences were observed for the tand peak amplitude. They were related to the morphology of the system, i.e., dispersed zein aggregates in starch matrix or dispersed amorphous starch in zein matrix, the phase inversion domain, determined by image analysis, being in the (17-34%) phase concentration interval. When testing processed corn flour under different thermomechanical conditions, at a moisture content of 12.0% (wb), higher values of tand peak were found when starch transformation was increased. For the same trend, values of E' modulus in the rubbery state continuously decreased which was attributed to the reduction of remaining starch granules within the flour. The application of models of composites materials points out the matrix-particles behaviour of processed corn flour and starch-zein blends, whatever the particles composition. The quality of adhesion between starch and zein is inferred for the mechanical properties of their blends.
H. Chanvrier, G. Della Valle, D. Lourdin, Carbohydrate Polymers 65 (2006) 346-356

B2024 – Relationships between texture, mechanical properties and structure of cornflakes

Hominies and flours derived from four corn varieties were prepared according to industrial recipes and processed as petals by extrusion cooking (SME = 150 J g-1, Tdie = 130°C) and a batch thermal process (100°C, 50 min). Flake texture was evaluated by crushing bulk petals in a Kramer cell and comparing measurements to those obtained for commercial cornflakes, previously graded by a trained sensory analysis panel. Depending on the corn variety, various results were found in regard to crispness. Bending moduli of dense extruded materials (Es from 0.5 to 2.1 GPa) were found to be correlated to the texture of petals derived from the same blends. Results obtained at different scales showed that the expanded microstructure of flakes, determined by X-ray tomography, and the morphology of their constitutive materials, deduced from confocal scanning light microscopy and RVA, primarily depended on the process used rather than on the corn variety. Adhesion between protein aggregates and amorphous starch matrix was inferred from the mechanical properties involved in texture.
L. Chaunier, G. Della Valle, D. Lourdin, Food Research International 40 (2007) 493-503

B2023 – Fractionation of extracted Madagascan Gracilaria corticata polysaccharides: Structure and properties

Polysaccharides were sequentially extracted from Gracilaria corticata which is collected from south-west coast of Madagascar. Chemical analysis combined with 1H, 13C NMR and Fourier transform infrared spectroscopies showed that the fraction extracted with water/ ethanol 60% (v/v) as solvent has low methoxyl and pyruvate contents and a great ability to form relatively strong physical gels in the presence of KCl. Rheological properties of extracted fractions are discussed as well as the ionic selectivity.
H. Andriamanantoanina, G. Chambat, M. Rinaudo, Carbohydrate Polymers 68 (2007) 77-88

B2016 – Heat denaturation and aggregation of beta-lactoglobulin enriched WPI in the presence of arginine HCl, NaCl and guanidinium HCl at pH 4.0 and 7.0

The heat denaturation and aggregation behaviour of beta-lactoglobulin (beta-LG) enriched WPI was investigated at pH 4.0 and 7.0 in the presence of arginine HCl, NaCl and GdnHCl using differential scanning calorimetry (DSC) and dynamic light scattering (DLS). Beside the classical endothermic signal attributed to protein heat denaturation, DSC thermograms displayed appearance of an additional exothermic peak in the presence of cosolute. Using in situ DLS, it was shown that the appearance of the exothermic peaks is linked to protein aggregation, in particular to a strong increase in aggregate size. Upon increased cosolute concentration at pH 4.0 the exothermic peak occurred at temperatures lower than the actual denaturation peak ( ~85°C). At this pH, negatively charged chloride anions interact with beta-LG leading to charge screening and physical aggregation. At pH 7.0, exothermic peaks appeared at higher temperatures than the denaturation peak ( ~75°C). Upon increased cosolute concentration the exothermic peak was shifted to lower temperatures, indicating protein destabilisation in the presence of cosolutes. Charge screening of beta-LG by the positively charged cations (arginine, Na and guanidinium) reduced repulsion forces and promoted aggregation.
G. Unterhaslberger, C. Schmitt, C. Sanchez, C. Appolonia-Nouzille, A. Raemy, Food Hydrocolloids 20 (2006) 1006-1019

B1962 – Influence of incubation temperature and time on resistant starch type III formation from autoclaved and acid-hydrolysed cassava starch

Raw cassava starch, having 74.94 and 0.44 g/100 g resistant starch type II and III (RS II and RS III), respectively, was autoclaved at 121°C in water, 1, 10 or 100 mmol/L lactic acid. The formation of RS III was evaluated in relation to variable incubation temperature ( 20 to 100°C), incubation time (6-48 h) and autoclaving time (15-90 min). Negligible to low quantities of RS III (0.59-2.42 g/100 g) were formed from autoclaved starch suspended in 100 mmol/L lactic acid, whereas intermediate to high quantities (2.68-9.97 g/100 g) were formed from autoclaved starch suspended in water, 1 or 10 mmol/L lactic acid, except for treatments with water or 10 mmol/L lactic acid incubated at 100°C for 6 h (1.74 g/100 g). Autoclaving times corresponding to maximum RS III contents were 15 and 45 min for water and 10 mmol/L lactic acid, respectively. Whereas, the RS III fractions from cassava starch suspended in water had melt transitions between 158 and 175°C with low endothermic enthalpies (0.2-1.6 J/g), the thermal transitions of the acid treated samples were indistinct.
C. Onyango, T. Bley, A. Jacob, T. Henle, H. Rohm, Carbohydrate Polymers 66 (2006) 494-499

B1944 – Influence of tempering on the mechanical properties of whipped dairy creams

Bulk rheological properties of natural whipped creams during and after a tempering treatment were followed. Tempering consisted of warming the systems up to a temperature between 15 and 30°C and cooling down to 4°C. Owing to this treatment, whipped creams clearly stiffened and could be stored for several weeks without any visible structural change. The storage modulus, G', exhibited a dramatic increase when tempering was applied immediately after whipping and this modulus was used as an indicator of the tempering efficiency. An increase of the fat globule connectivity due to partial coalescence was one of the main factors explaining the consolidation of whipped creams.
N. Drelon, E. Gravier, L. Daheron, L. Boisserie, A. Omari, F. Leal-Calderon, International Dairy Journal 16 (2006) 1454-1463

B1911 – Characteristics of mung bean starch isolated by using lactic acid fermentation solution as the steeping liquor

Physicochemical properties of commercial mung bean starch isolated with lactic acid fermentation solution (LFS) and starches laboratory- prepared by using NaOH, Na2SO3 and distilled water as steeping liquors were examined with the aim of elucidating the effect of different steeping liquors on the properties of starches. Results indicated that the amylose content, granular morphology and X-ray diffraction pattern of starches isolated with different steeping liquors did not show obvious differences. However, the LFS-isolated starch had significantly (p < 0.05) higher weight percentage of longer B chains and B1 chains, a lower weight percentage of A chains and a lower ratio of short-to-long chains in amylopectin than those of the other preparations. Moreover, the LFS-isolated starch showed significantly (p < 0.05) lower pasting viscosity, a higher onset temperature, a narrower temperature range and a lower enthalpy of gelatinization than the other preparations. No significant differences on the physicochemical properties mentioned above were found among the laboratoryprepared starches. The results suggest that mung bean starch is degraded during isolation with lactic acid fermentation solution, which leads to the loss of starch granules with less integrity.
Y-H. Chang, C-L. Lin, J-C. Chen, Food Chemistry 99 (2006) 794-802

B1897 – Comparison of curdlan and its carboxymethylated derivative by means of Rheology, DSC, and AFM

Curdlan was carboxymethylated in an aqueous alkaline medium using monochloroacetic acid as the etherifying agent. The structure of carboxymethylated curdlan (CMc) was analyzed by FT-IR and NMR spectroscopy, which revealed that the carboxymethyl group was introduced mainly at the C-6 position as well as at the C-2 and C-4 positions. Furthermore, CMc was compared with the native curdlan by using rheology and DSC methods. It was found that in water, both polysaccharides behaved as pseudoplastic fluids and fit the power law and Herschel-Bulkley rheological models well. Both the storage shear modulus G' and the loss shear modulus G" of CMc aqueous solutions decreased and became more frequency dependent with decreasing concentration in comparison with the curdlan aqueous suspensions. The modulus-temperature curve also suggested that the gel characteristic of curdlan has been lost after chemical modification, which is consistent with the DSC results. AFM images revealed differences in the conformation of native and carboxymethylated curdlan, which changed from the aggregation of macromolecules to triple helices. All the experimental results suggest that the hydrogen bonds that bind curdlan with interstitial water to form the micelles have been destroyed completely and that the hydrophobic interactions related to the methylene groups at C-6 formed above 55°C disappeared due to the introduction of the hydrophilic carboxymethyl group.
Y. Jin, H. Zhang, Y. Yin and K. Nishinari, Carbohydrate Research 341 (2006) 90-99

B1893 – Phase behavior and rheological properties of enzymatically synthesized trehalose decanoate aqueous solutions

Surface tension properties of an enzymatically synthesized equimolar mixture of trehalose mono- and didecanoate in aqueous solutions have been determined. At 20°C a critical micellar concentration (CMC) of 50 µmol/l and a minimal surface tension of 28 mN/m have been obtained. Above the CMC, it has been shown that up to a concentration of 42 wt%, and in a 20-60°C temperature range the sugar ester aqueous solutions do not form any crystalline structure, nor present any phase transition, and the trehalose decanoate molecules form an isotropic worm-like micellar phase. The rheological properties indicate however a more complicated picture in the same concentration and temperature ranges. In steady shear, the viscosity of the trehalose decanoate solutions do not exhibit any shear rate dependence from 1 to 100 s-1 for concentrations up to 42 wt%. Below 0.8 wt%, the viscosity remains constant and close to that of water; then, between 0.8 and 23 wt%, the viscosity shows a quadratic increase with surfactant concentration. For higher concentrations, up to 42 wt%, no further significant increase in viscosity is observed. In oscillatory shear experiments, the solutions exhibit viscoelastic properties. The observed rheological behavior as a function of concentration and temperature may be due to a progressive evolution of the trehalose decanoate molecular associations: as the concentration increases, the system evolves towards an entangled and/or partially branched or cross-linked micellar network, and eventually a multiconnected network of cross-linked micelles.
L. Choplin, V. Sadtler, P. Marchal, D. Sfayhi, M. Ghoul, J.-M. Engasser, Journal of Colloid and Interface Science 294 (2006) 187-193

B1879 – Denaturation and aggregation processes in thermal gelation of whey proteins resolved by differential scanning calorimetry

Gelation of globular proteins on heating involves two separate stages. The first is partial unfolding (denaturation) of the native globular structure; the second is intermolecular aggregation. Denaturation involves dissociation of intramolecular bonds (non-covalent and, in some cases, disulfide) and is therefore an endothermic process. The aggregation step involves formation of new bonds between protein molecules, and would therefore be expected to give a differential scanning calorimetry (DSC) exotherm on heating, but numerous previous studies of the thermal gelation of whey proteins, carried out on conventional (fast scanning) DSC calorimeters (typical sample mass 15-50 mg), have shown only endothermic transitions. In the present work, however, we have observed the endothermic (denaturation) and exothermic (aggregation) processes in thermogelation of whey protein isolate (WPI) as separate transitions in DSC heating traces recorded on a Setaram microcalorimeter (sample mass 850 mg). Under conditions where aggregation occurs much more slowly than denaturation (low protein concentration; low ionic strength) the two transitions are well resolved, with the exotherm from aggregation following the endotherm from denaturation. The position of the exotherm, however, appears to be time-dependent rather than temperature-dependent. On reduction in heating rate, the apparent peak-maximum temperature of the aggregation exotherm decreases towards the (essentially constant) position of the denaturation endotherm, and, at sufficiently low scan rates, the exotherm becomes obscured by the more intense endotherm. Progressive displacement of the exotherm into the temperature range of the denaturation endotherm also occurs in response to changes that accelerate intermolecular aggregation and accompanying gelation (addition of salt; increasing protein concentration). The absence of a detectable exotherm in previous studies using conventional calorimeters is attributed to the much smaller sample mass than in the Setaram instrument, giving much faster heat transfer, which may cause the exothermic heat flow from the slow aggregation process to be swamped by the endothermic heat flow from the more rapid denaturation process.
S.M. Fitzsimons, D.M. Mulvihill, E.R. Morris, Food Hydrocolloids 21 (2007) 638-644

B1866 – Effects of non-ionic polysaccharides on the gelatinization and retrogradation behavior of wheat starch

Gelatinization and retrogradation behavior of wheat starch in an aqueous system was studied by rheological and thermal techniques in the presence or absence of non-ionic polysaccharides, including guar gum, tara gum, locust bean gum, and konjac glucomannan. Macromolecular characteristics of each polysaccharide, including weight-average molecular weight Mw and radius of gyration Rg; were determined by static light-scattering, resulting in (1.0-3.2) x 10^6 g/mol for Mw and 104-217 nm for Rg; respectively. During gelatinization, addition of each polysaccharide (0.5-1% w/v) increased peak viscosity for the starch system (13%): 163-231 unit larger than the control at 0.5%, whereas 230-437 unit larger at 1%. Among the galactomannans tested, the order of this effect (locust . tara . guar) was contrary to that of the molecular size (guar . tara . locust). During short-term retrogradation, addition of each polysaccharide (0.5%) increased dynamic mechanical loss tangent (tan delta) for the starch system (5%) after storage at 4°C for 24 h: (16.5-26.9) x 10^(-2) unit larger than the control. Among the galactomannans tested, the larger the molecular size, the greater the effect to increase tan d; and this effect of polysaccharide was not explained simply by the difference in the amount of amylose leached during gelatinization. During long-term retrogradation, addition of each polysaccharide (0.5%) decreased the rate constant expressing the relationship between storage time (for 14 days at 4°C) and creep compliance for the starch system (15%): (0.9-1.5) x 10^(-2) unit smaller than the control. Among the galactomannans tested, the larger the molecular size, the greater the effect to decrease the rate constant. Functions of polysaccharide to starch were hypothesized considering structural compatibility and molecular interactions between polysaccharide and starch components; amylose and amylopectin.
T. Funami, Y. Kataoka, T. Omoto, Y. Goto, I. Asai, K. Nishinari, Food Hydrocolloids 19 (2005) 1-13

B1865 – Structure and mechanical behaviour of corn flour and starch-zein based materials in the glassy state

Corn flour and starch-zein based samples were prepared by extrusion and thermomoulding and then analysed at a moisture content of 12.0% (wb). Starch-zein blends (5-50% zein, db) were used to study the influence of starch-zein ratio on material properties. Glass transition temperatures were determined by differential scanning calorimetry and molecular relaxations by dynamic mechanical thermal analysis. Behaviour at large deformations was examined by the three-point bending test. The behaviour of materials made from glassy corn flour and starch-zein blends was compared to the behaviour of their components. Amorphous starch was ductile whereas blends and corn flour samples were brittle. This difference could not be explained by molecular mobility. Blend morphology observed by confocal scanning light microscopy (CLSM) showed that proteins undergo aggregation during thermomechanical processing, which largely conditioned their mechanical properties. The consequences of processing on the morphology of the protein phase in the corn flour were also discussed.
H. Chanvrier, P. Colonna, G. Della Valle, D. Lourdin, Carbohydrate Polymers 59 (2005) 109-119

B1850 – High-pressure treatment effects on proteins in soy milk

Effects of high-pressure treatment on the modifications of soy protein in soy milk were studied using various analytical techniques. Blue shifts of lmax could be observed in the fluorescence spectra. Spectrofluorimetry revealed that the soy protein exhibited more hydrophobic regions after high-pressure treatment. Electrophoretic analysis showed the change of soy protein clearly and indicated that soy proteins were dissociated by high pressure into subunits, some of which associated to aggregate and became insoluble. High-pressure denaturation occurred at 300MPa for beta-conglycinin (7S) and at400 MPa for glycinin (11S) in soy milk. High pressure-induced tofu gels could be formed that had gel strength and a cross-linked network microstructure. This provided a new way to process soy milk for making tofu gels.
H. Zhang, L. Li, E. Tatsumi, S. Isobe, Lebensm.-Wiss. u.-Technol. 38 (2005) 7-14

B1840 – Water properties in wheat flour dough II: classical and knudsen thermogravimetry approach

Thermo-Gravimetric Analysis (TGA) investigations suggest that water in a wheat flour dough is partitioned in various states related to the different disperse phases of the system. Classical TGA results indicate the gross water partition at the macroscopic level, while Knudsen TGA investigations, that allow evaluation of the relative humidity of the dough at room temperature, suggest the involvement of water in the structure of the dough at a supra-molecular level. The overall moisture content, the mechanical stresses and the presence of extra non-starch polysaccharides and/or soluble proteins, can affect this partition, either promoting water displacements across the inter-phases, or modifying the supra-molecular structure of the system. The investigations, extended to bread crumb during ageing, indicate that water undergoes displacements and forms stronger links with the components of the aged crumb with a kinetic law that can be influenced by the presence of extra non-starch polysaccharides.
D. Fessas, A. Schiraldi, Food Chemistry 90 (2005) 61-68

B1796 – Factors affecting fat droplet aggregation in whipped frozen protein-stabilized emulsions

We studied four emulsions, stabilized by milk proteins, before and after application of whipping and freezing procedure. The emulsions were different in the whey protein/casein ratio and degree of heat-denaturation before mixing with the other ingredients. The supercooling needed for detection of crystalline fat was higher in emulsions than in bulk fat, and higher in emulsions containing casein or heat-denatured whey proteins than in emulsion containing non-pre-heated whey proteins. Furthermore, emulsions with high surface protein concentration and low crystalline fat content showed greater droplet aggregation under whipping and freezing. Our results indicated that differences in sensitivity to fat droplet aggregation was not caused by differences in resistance to protein displacement from the droplet surface in thawed whipped emulsions, but by low crystalline fat content prior to whipping and freezing. Data collected in this study were discussed in terms of effects of partial replacement of 'native' whey proteins by casein or heat-denatured whey proteins on partial coalescence of fat droplets in whipped-frozen emulsions.
P. Relkin, S. Sourdet, Food Hydrocolloids 19 (2005) 503-511

B1788 – Properties of starches from cocoyam (Xanthosoma sagittifolium) tubers planted in different seasons

Starch was extracted from the tubers of two cocoyam (Xanthosoma sagittifolium) cultivars (KCX01 and KCX02) planted in three different seasons (summer, winter and spring). Physicochemical properties of the starch were determined in order to investigate the seasonal effect on cocoyam starch. Cocoyam tubers planted in the summer showed higher contents of total starch than tubers planted in other seasons. Starches from both cultivars of cocoyam tubers planted in the summer season had significantly (p<0.05) higher average granule sizes, higher contents of amylose, higher ratios of short-to-long chains of amylopectin, and lower values of the average degree of polymerization (DP) of the chain length distribution profiles. The distinct properties of the fine structure of cocoyam starch from tubers planted in summer season were associated with lower values of onset and peak temperatures and enthalpies of gelatinization.
T-J. Lu, J-C. Chen, C-L. Lin, Y-H. Chang, Food Chemistry 91 (2005) 69-77

B1678 – Isoperibol calorimetry as a tool to evaluate the impact of the ratio of exopolysaccharide-producing microbes on the properties of sour cream

The quality of sour cream production from homogenised cream in the 1970's was highly improved. The heat resistance of product remained badly, that is, it precipitated in hot food. The Hungarian Dairy Research Institute (HDRI) has elaborated a technology that eliminates this disadvantageous characteristic: it is the use of exopolysaccharide (EPS)-producing lactic acid bacteria. This bacterium produces no aroma, and the proliferation optima of EPS-producing and aroma-producing lactic acid bacteria cultures do not coincide. Detection of these two bacteria was done until now by gene technology, that is expensive and long lasting one. We have applied (at first as we know) isotherm calorimetric method to follow the simultaneous proliferation of these bacteria and it was determined that: both lactic acid bacteria cultures proliferate well at the non-optimal temperature of 30°C and the thermophilic EPS-producing culture was faster than that of the mesophilic aroma-producer. The two cultures do not inhibit each other in mixed culture, and the ratio in mixed culture was 79% EPS-producer and 21% aroma-producer.
B. Schäffer and D.Lörinczy, Journal of Thermal Analysis and Calorimetry 82 (2005) 537-541

B1674 – Examination of the correlation of butter spreadability and its fat conformation by DSC

Since the appearance of margarines and spreads on the market, they have been serious competitors with butter. One of the reasons for this was the false nutritional propaganda, but today butterfat has scientifically regained its actual nutritional evaluation. The main disadvantage of butter in comparison to other spreadable tallow is that it does not immediately spread as well when taken out of the refrigerator. One method of obtaining better cold-spreadability is appropriate cream ripening in which a different system known as the corpuscular colloid is created. Recent examinations were conducted during the winter, when the problem of spreadability of butter is the greatest. Simple cold ripening in accordance with the method used in our earlier EPR studies ripened the cream, and by heat-step ripening, then butter was produced from these materials. By deconvolutional analysis of the DSC curves it was established that butter made from the cream ripened by the heat-step method had three characteristic melting peaks as distinct from the two melting peaks of butter made from cold-ripened cream, and the temperature of the second melting peak for butter from heat-step cream was identical to the characteristic melting temperature for fat particles from earlier EPR spectroscope assays. In sum it can be stated that the DSC method clearly shows both the homogeneous and the particle structure characteristic of butter.
B. Litz, G. Obert and B. Szily, Journal of Thermal Analysis and Calorimetry 84 (2005) 425-428

B1659 – Thermal stability, texture, liquid holding capacity and colour of smoked salmon on retail level

Retail samples of vacuum-packed sliced cold smoked salmon were investigated for changes in texture, colour and expressible moisture approximately 1 week before expiry date and on the best before date. For comparison, retail samples of gravelax were also investigated. To gather information on alteration in protein caused by processing and refrigerated storage, DSC measurements were performed at the same samples and furthermore on hot smoked salmon and frozen raw material, Salmo salar. Texture parameters varied markedly between the retail samples; however, almost no clear tendencies were observable with increased refrigerated storage time while expressible moisture raised. Colour also differed considerably between the samples. Gravelax behaved almost comparable to cold smoked salmon. DSC curves taken from cold smoked salmon and gravelax were almost comparable and demonstrated that muscle proteins being largely denatured by the influence of salt and cold smoking temperature compared to the raw material.
Reinhard Schubring, Thermochimica Acta 445 (2006) 168-178

B1610 – Detection of probiotic microbes in probiotic cheese spreads by isothermic calorimetry

The probiotic cheese spreads developed by the Hungarian Dairy Research Institute (HDRI) have a better Ca:P ratio than traditional brands and spread easily and without sticking even cold, further, their live lactic acid bacteria content gives them additional advantages as well. These advantages derive from the fact that a probiotic culture may also be employed during fermentation, through which the cheese spread may become probiotic if the culture proliferates. The international specification is a probiotic cell count of at least 10^6/g. However, during fermentation the probiotic cheese spread must also use other non-probiotic cultures to produce the right taste. Given that the microorganisms in the cultures are all cocci, their indication in a mixed environment is difficult and time-consuming. It appears possible, therefore we have used the isothermic DSC method due to their differences in heat production. In order to analyze the calorimetric curves a deconvolutional program was devised which decomposed them into Gaussian curves. It was confirmed that probiotic bacteria proliferated in the probiotic cheese spreads, and their ratio was greater than 40% with a total plate count of 2-7 x 10^8/g. Accordingly, the probiotic cheese spread developed by HDRI contains an order of magnitude more probiotic bacteria than the internationally accepted cell count of 10^6/g.
B. Szily, G. Obert and B. Schaffer, Journal of Thermal Analysis and Calorimetry 82 (2005) 245-247

B1578 – Methodology for lifetime prediction : A study to evaluate the thermal stability of frozen and fresh herring using Micro DSC

B. Roduit, R. Naumann (2006)

B1568 – Thermal behaviour of emulsifier-water systems studied by microDSC

Emulsifiers are often used in the food industry to stabilize interfaces in emulsions and foams, for example. When added to an aqueous phase, emulsifiers form spontaneously self-assembly structures. Such structured fluids can be used for active ingredients encapsulation or as micro-reactors for flavour formation. In the present paper we describe the potentialities of DSC, mainly micro-DSC, to study phase transitions of emulsifiers alone and with addition of water. The main role of the calorimetric techniques will probably be to precisely determine melting and crystallization zones, to inform about polymorphism and hysteresis due to undercooling, and especially to follow the effects of guest molecules on the weak liquid crystal transitions. Micro-DSC, when compared to other techniques, generally allows measurements over an extended temperature range.
A. Raemy, C. Appolonia Nouzille, P. Frossard, L. Sagalowicz, M-E. Leser, Journal of Thermal Analysis and Calorimetry 80 (2005) 439-443

B1543 – L’analisi termica DSC del sughero (the DSC thermal analysis of cork)

C. Pagella, P. Silvestri, D.M. de Faveri, G. Parodi, Industrie delle Bevande XXV (1996) 430-435

B1542 – Stabilita termica dell’acido ascorbico e dell’eritorbato di sodio

In some processing industries thermal treatments of thermal unstable substances are performed, with important implications for the quality of products. In these processes the design of plants must include constraints to operating variables to account for these phenomena on the basis of the theory of thermal stability. For example, in the processing of sodium erythorbate and ascorbic acid these facts are particularly important due to easy decomposition of the high value added product and strict quality requirements of food applications. Studies of decomposition of the products by DSC can be useful to identify reaction and kinetics parameters and relate them to the main parameters influencing thermal processes.
G. Spigno, D.M. de Faveri, P. Perego, Industrie Alimentari 38 (1999) 538-545

B1541 – Gelatinization kinetics of rice starch studied by non-isothermal calorimetric technique : influence of extraction method, water concentration and heating rate

Different rice starch samples were obtained varying extraction solution, soaking temperature and length. Gelatinization properties were determined at different water concentrations by differential scanning calorimetry at constant heating rate, revealing no influence by the extraction parameters. Gelatinization kinetics were studied on starch extracted for 6 h with 0.2% NaOH, at 30°C with the aim of comparing some mathematical methods, in order to find whether this technique could be used to estimate the kinetic parameters. Activation energy and order of reaction were calculated at different water:starch ratios and heating rates, to partly simulate the wide variety of conditions for processes where starch gelatinization is involved. Water content influenced both gelatinization enthalpy and Ea, while heating rate influenced the temperature. Non-isothermal DSC was able to characterize the gelatinization process only if the kinetics of the process were already known, since all the tested models well fitted experimental data but gave quite different values of Ea.
G. Spigno, D.M. de Faveri, Journal of Food Engineering 62 (2004) 337-344

B1536 – Calorimetric observation of lactose crystallisation in skim milk and whey protein concentrate powders

During the manufacture and storage of dairy powders and ingredients, physical changes such as lactose crystallisation and chemical modifications such as Maillard reactions may change the functionality of the powders. The main goal of the present calorimetric study was to investigate lactose crystallisation in skim milk (SMP) and whey protein concentrate (WPC) as well as the effect of water activity. Microcalorimetry at low heating rates is shown to be efficient in this context as it allows to obtain good peak resolution in addition to the high sensitivity of the instrument. The main results showed that lactose crystallisation was easily induced in SMPs, whereas it was delayed or inhibited in WPCs, even when the lactose content of both powders where the same. These results help to understand the role played by protein structure and protein/sugar/water interactions in the physico-chemical stability of dairy powders and ingredients.
A. Raemy, F. Morgan, R. Baechler, C. Appolonia Nouzille, G. Vualaz, PhanTA (2004 )

B1529 – Kinetics of gelatin transitions with phase separation: T-jump and step-wise DSC study

The isothermal gelation (or melting) of gelatin after fast cooling (or heating) steps is studied by using high sensitivity differential scanning micro-calorimetry, in order to determine the dependence of the kinetic and thermodynamic parameters upon changes in composition and in temperature. The calorimetric heat flow curves, obtained according to defined temperature profiles, have been fitted with exponential functions (simple exponentials or stretched exponentials for the step-wise and for T-jump experiments, respectively). The gelation process of gelatin alone for t<300 min shows that the characteristic time t and the fractional exponent are beta very sensitive to the concentration of gelatin chains and to the microscopic phase segregation due to the presence of another polymeric component.
F. Cuppo, M. Venuti, A. Cesaro, International Journal of Biological Macromolecules 28 (2001) 331-341

B1527 – Simultaneous heat-flow differential calorimetry and thermogravimetry for fast determination of sorption isotherms and heat of sorption in environmental or food engineering

A new experimental technique is described for the determination of desorption characteristics for engineering purposes. A TGA-DSC set-up is used in isothermal mode to achieve the thermal desorption of deformable standard materials like microcrystalline cellulose and kaolin in dry air. Assumptions on heat and mass transfer are made and discussed in order to derive desorption isotherms and heat of sorptions from the calorimetric and gravimetric signals. The method is rapid and accurate for high-temperature desorption processes T>40°C. It is particularly reliable for small water activity values 0
J-H. Ferrasse, D. Lecomte, Chemical Engineering Science 59 (2004) 1365-1376

B1496 – Calorimetric and rheological properties of wheat flour suspensions and doughs. Effects of wheat types and milling procedure

Three types of wheat were submitted to two different milling procedures, giving rise to six flours which differed by some physico-chemical characteristics such as particle size, level of damaged starch and protein content. Differential scanning calorimetry was used for monitoring heat-induced structural changes in flour aqueous dispersions 80% water and in doughs 45% water. Differences between the thermal behaviour of the flour dispersions and doughs were explained mainly by differences in protein content. This result was confirmed after partial substitution of flour by gluten. Dynamic mechanical analysis performed at 20°C on the flour doughs indicated, as expected, a linear increase in the elastic modulus with increasing protein content. The results did not bring any evidence that, under these experimental conditions, starch damage might affect gluten hydration.
S. Berland, P. Relkin, B. Launay, Journal of Thermal Analysis and Calorimetry 71 (2003) 311-320

B1494 – Classical and Knudsen thermogravimetry to check states and displacements of water in food systems

Water states and displacements can be investigated with thermogravimetry (TG) either in its classical or in the Knudsen version (where standard pans are replaced with Knudsen cells). The case of wheat flour dough is considered in various steps of bread making, namely, mixing, proofing, baking, staling. The split of DTG signals into various components (gaussian functions) support the assumption that the overall dough water is partitioned into various fractions. Few comments are devoted to water displacements during freezing.
A. Schiraldi, D. Fessas, Journal of Thermal Analysis and Calorimetry 71 (2003) 225-235

B1481 – Examination of the growth of probiotic culture combinations by the isoperibolic batch calorimetry

Probiotic ("intestinal friend") foods, and probiotic dairy products in particular, have substantially increased in number recently. In the production of some of these products a problem is caused by the fact that the thermotolerant microbes that produce the probiotic effect do not generate an aroma; the taste of the product is given by aroma-producing mesophilic microbes. The growth optima of the two microbe groups do not coincide. Given that heat is released in the course of microbe reproduction, the isoperibolic calorimetry method appears the best and fastest for monitoring the process. During the experiments the thermotolerant Prebiolact, owned by the Hungarian Dairy Research Institute (HDRI) and clinically verified to be probiotic, and Hansen Company's CHN-22 mesophilic butter culture were examined bred separately and together. The cultures were incubated at 30°C, at which temperature prior studies had shown both lactic acid bacteria cultures were capable of growing. The cultures were injected into milk, then the microbe growth heat flow-time curve over 18 h was taken on the Setaram Micro DSC-II calorimeter at 30°C under isothermic conditions. Analysis of the heat flow curves led to the following conclusions. Both lactic acid bacteria cultures grow well at the non-optimal temperature of 30°C, thermotolerant Prebiolact somewhat faster and mesophilic CHN-22 slower. The two cultures do not impede each other in mixed cultures; the growth peaks of the two cultures were easily isolated on the power-time curve by a deconvolution program. In sum it can be stated that mixed cultures of the two cultures examined can be used to produce dairy products which are probiotic, but their taste character (e.g. aroma) is determined by the butter culture. To date we have elaborated production procedures for probiotic butter cream and heat-resistant sour cream using the two cultures in a mixed one.
B. Schäffer, S. Szakaly, D. Lörinczy, Thermochimica Acta 415 (2004) 123-126

B1472 – Coupling of heart rate with metabolic depression in fish : a radiotelemetric and calorimetric study

This study of the goldfish (Carassius auratus L.) combines two techniques: heat measurements via direct calorimetry and radio telemetry, using small implantable telemetry transmitters (3 g). These record overall metabolic rate, and electrocardiogram (ECG) and heart rate frequency (fHR), respectively. The metabolic rate decreased at hypoxia levels of 40, 20, 10, and 3% air-saturation (AS) almost linearly to 94, 84, 69, and 55% of the standard metabolic rate (SMR), respectively. This implies that metabolic depression is flexible, depending on the supply of oxygen. From the deconvoluted heat-flow signal it can be concluded that the metabolic depression per hypoxia level takes place within 20 min. At 3% AS anaerobic metabolism was strongly activated. The fHR of 34 beats per minute (bpm) at normoxia fell at hypoxia levels of 40, 20, 10, and 3% AS to 26, 22, 14, and 9 bpm, respectively. A correlation coefficient of 0.97 was calculated between the level of metabolic depression and decrease of fHR suggesting a relationship between level of metabolic depression and the HR. These results support the hypothesis that blood flow reduction is the proximate cause for the observed metabolic depression.
V.J.T. van Ginneken, P. Snelderwaard, R. van der Linden, N. van der Reijden, G.E.E.J.M. van den Thillart, K. Kramer, Thermochimica Acta 414 (2004) 1-10

B1468 – DSC and electrophoretic studies on soymilk protein denaturation

The effects of heat treatment on soymilk protein denaturation were studied by differential scanning calorimetry (DSC) and electrophoresis. Transition behavior of soymilk was studied by DSC. Three endotherms were found in DSC heating curves; the transition observed at around 70°C is attributed to the denaturation of 7S (-conglycinin) and the transition at around 90°C is to 11S (glycinin). The denaturation temperature increased with the increasing soymilk protein content. The change of electrophoretic patterns after heat treatments indicated that soy proteins were dissociated into subunits, some of which coalesced. When the heating temperature is below their denaturation temperature, the protein fractions cannot completely be denatured even after heat exposure for extended periods of time.
H. Zhang, M. Takenaka, S. Isobe, Journal of Thermal Analysis and Calorimetry 75 (2004) 719-726

B1372 – Comparative studies on gamma radiation and high pressure induced effects on minced beef

The total viable cell count of bacteria in vacuum-packaged chilled minced beef has been decreased equally, by approx. two log-cycles, as an effect of 1.5-2.0 kGy gamma radiation or 200-300 MPa high hydrostatic pressure (UHP) treatment for 20 min. Coliform bacteria could be eliminated to non-detectable levels by the same treatments. The shelf-life of both untreated and non-thermally pasteurised samples were limited mainly by growth of lactic acid bacteria. At about equal bactericidal effect, more drastic changes of texture and colour occurred in UHP-pasteurized minced beef samples than in the radiation-pasteurized ones. Whereas radiation pasteurisation caused minimal changes in appearance, texture and DSC-thermograms of minced beef, UHP-pasteurisation of the raw samples proved to be strongly discolouring by denaturing the muscle pigments and causing extensive denaturation of the myofibrillar proteins. The water holding capacity of irradiated samples decreased, while that of high pressure treated ones increased as compared to the untreated control. Near infrared spectrometry and electronic nose measurements gave promising results to make distinctions non-destructively on changes of various physical-chemical changes and quality parameters as a function of pasteurising treatments and/or storage.
Y. Hassan, L. Meszaros, A. Simon, E. Tuboly, CS Mohacsi-Farkas, J. Farkas, Acta alimentaria 31 (2002) 253-264

B1364 – Gelatinization and retrogradation of corn starch with different amylose/amylopectin ratios

Miyako Hayashi, Katsuyoshi Nishinari - 38th japanese conference on calorimetry & thermal analysis pp 42-43

B1328 – Processed cheeses made with and without peptization – Submicroscopic structure and thermodynamic characteristics

The osteoporosis is regarded as a widespread disease all over the world. In the prevention therapy of this disease there is a primary role of the daily calcium intake with the proper Ca:P ratio (1:1-1:2). The primary source of Ca for people the dairy products are implied, from which only the processed cheeses have inadequate ratio of Ca:P. In cheeses processed without peptization developed in the Hungarian Dairy Research Institute (HDRI) the Ca:P ratio meets the requirements (1.5:1), moreover these products can be enriched with Ca. In this study we used both processing technologies. The electronmicroscopic photographs demonstrate the differences clearly. The traditionally processed cheese (with peptization) has a spongy structure well known from literature, while a space-net can be seen resulting from the casein-filamentous hydrocolloid interaction in the structure of heat-treated cheese without peptization. DSC curves are the same in the temperature range 0-40°C, showing endotherm melting process in two well-distinguished temperature interval (0-20 and 22-40°C). They are different in the temperature interval 40-100°C: in the case of processed cheese with peptization the gel-sol transformation gives a higher endotherm peak in a narrow temperature range, while for heat-treated cheese without peptization this temperature range is wider with a lower endotherm peak. Both electronmicroscopic and DSC investigations have proved that contrary to the traditionally processed cheese where the structure is formed by the linked peptized protein, in the heat- processed cheese without peptization the frame-forming element is the huge hydrocolloid molecule interacted with the protein. The enthalpy change is substantially lower at the disintegration of the latter structure.
B. Schäffer, S. Szakaly, D. Lörinczy, B. Schäffer, Journal of Thermal Analysis and Calorimetry 64 (2001) 671-679

B1327 – Melting properties of butter fat and the consistency of butter – Effect of modification of cream ripening and fatty acid composition

The cold unspreadable consistency of butter after taking it out of the refrigerator is a rightful objection on behalf of consumers. The possibilities to improve the cold spreadability of butter are: the enrichment with low melting point triglycerides and the application of a good cream-ripening method. In our investigations milk fat fractions of different low melting points and plant oils of low melting points obtained by cold pressing and extraction have been used to change the original fatty acid composition of milk fat. The cream-ripening, the traditional method and the heat-step ripening method, which seemed to be the most effective to our earlier research, have been applied. The consistency of butter was examined by penetration measurements and its thermal characteristics by differential scanning calorimetric (DSC) method. The cold unspreadable consistency of butter can only be improved by the combination of the heat-step cream ripening and enrichment with low melting point triglycerides to get stable consistency at room temperature. The milk fat fraction of melting point below 5°C made the spreadability better but the spreadable consistency of margarine still cannot be attained. Plant oils with melting point below 0°C improved the cold spreadability of butter to a significantly higher degree than the former did. In the case of the same melting point the plant oil obtained by a cold method (pressing) was more effective. There is a close relationship between the consistency of butter and its product characteristics. From DSC curves the cold spreadability and room temperature stability of butter can be directly concluded.
B. Schäffer, S. Szakaly, D. Lörinczy, B. Schäffer, Journal of Thermal Analysis and Calorimetry 64 (2001) 659-669

B1261 – Phase transition of apple cuticles : a DSC study

Apple and capsicum cuticles were isolated enzymatically from mature fruits and the effect of storage temperature on phase transition of the lipid components in the cuticle was examined using differential scanning calorimetry (DSC). It was found that the cuticular membrane underwent an endothermic transition attributed to melting of the waxes present in the cuticle. On storage at low temperatures the cuticular membrane underwent a change in structure and the melting enthalpy of the waxes present decreased as seen by DSC.
Poonam Aggarwal, Thermochimica Acta 367-368 (2001) 9-13

B1251 – Isothermal calorimetry approach to evaluate shelf life of food

Isothermal calorimetry (IC) traces were obtained at three temperatures for industrial whole-eggs, fresh milk and carrot convenience-salads to assess their durability when stored at various temperatures. According to the nature of the degradation process (microbial, metabolic (aerobic, or anaerobic), enzymatic), the order of magnitude of the exothermic signal recorded changed. The present work mainly aimed at determining the onset time of the calorimetric signal which was related to the stability (i.e. safe shelf life) of the food investigated. The higher the storage temperature, the earlier was the onset of the calorimetric signal: the temperature effect on the stability time could be, therefore, determined. This piece of information was used to choose time-temperature-integrators suitable for the products considered. Stability times for the three products were also evaluated with other approaches (microbial plate counts, pH variation, development of turbidity). The comparison between the results of these traditional techniques and the calorimetric monitoring supported the reliability of the latter, which offers some peculiar advantages, like better temperature control, continuous follow up, easier mathematical description, overall energy balance of the degradation process.
M. Riva, D. Fessas and A. Schiraldi, Thermochimica Acta 370 (2001) 73-81

B1241 – Protein inactivation in amorphous sucrose and trehalose matrices : effects of phase separation and crystallization.

Trehalose is the most effective carbohydrate in preserving the structure and function of biological systems during dehydration and subsequent storage. We have studied the kinetics of protein inactivation in amorphous glucose/sucrose (1:10, w/w) and glucose/trehalose (1:10, w/w) systems, and examined the relationship between protein preservation, phase separation and crystallization during dry storage. The glucose/trehalose system preserved glucose-6-phosphate dehydrogenase better than did the glucose/sucrose system with the same glass transition temperature (Tg). The Williams-Landel-Ferry kinetic analysis indicated that the superiority of the glucose/trehalose system over the glucose/sucrose system was possibly associated with a low free volume and a low free volume expansion at temperatures above the Tg. Phase separation and crystallization during storage were studied using differential scanning calorimetry, and three separate domains were identified in stored samples (i.e., sugar crystals, glucose-rich and disaccharide-rich amorphous domains). Phase separation and crystallization were significantly retarded in the glucose/trehalose system. Our data suggest that the superior stability of the trehalose system is associated with several properties of the trehalose glass, including low free volume, restricted molecular mobility and the ability to resist phase separation and crystallization during storage.
W.Q. Sun, P. Davidson, Biochimica et Biophysica Acta 1425 (1998) 235-244

B1240 – Protein stability in the amorphous carbohydrate matrix : relevance to anhydrobiosis.

The formation of intracellular glass is proposed to be relevant to protein stabilization and survival of anhydrobiotic organisms in the dry state. The stability of proteins in the amorphous carbohydrate matrix and its relevance to seed survival have been investigated in the present study. Glucose-6-phosphate dehydrogenase (G6PDH) was preserved in the amorphous glucose/sucrose (1:10, w/w) matrix by freeze-drying. The stability of freeze-dried G6PDH was examined at temperatures above and below the glass transition temperature (Tg). The rate of G6PDH inactivation in the amorphous carbohydrate matrix deviated significantly from the Arrhenius kinetics, and conformed to the Williams-Landel-Ferry (WLF) relationship. The temperature dependence of G6PDH inactivation in two sets of samples with different Tg values was compared. Identical temperature dependence of G6PDH inactivation was observed after temperature normalization by (T-Tg). Seed survival of Vigna radiata Wilczek (mung bean) showed a similar WLF kinetics at storage temperatures T > or = Tg. In situ protein stability in mung bean embryonic axes was studied using differential scanning calorimetry (DSC). Thermal stability of seed proteins exhibited a strong dependence on the Tg of intracellular glass. These results indicate an important role of the glassy state in protein stabilization. Our data suggest an association between protein stability in intracellular glass and seed survival during storage.
W.Q. Sun, P. Davidson, H.S.O. Chan, Biochimica et Biophysica Acta 1425 (1998) 245-254

B1213 – Some characteristics of hydroxypropylated and cross-linked rice starch.

Rice starch was cross-linked with phosphorus oxychloride (POCl3), hydroxypropylated with propylene oxide, and dual-modified with both reagents. The properties evaluated were: solubility in dimethyl sulfoxide, heat absorption during gelatinization, paste viscosity, and freeze-thaw stability. In addition, scanning electron microscopy was used to observe the morphology of the starch granules and their corresponding pastes. Cross-linking increased heat of gelatinization and shear stability, and it reduced solubility in dimethyl sulfoxide and freeze-thaw stability. Cross-linked starch exhibited a three-dimensional network structure under scanning electron microscopy. Opposite effects were found for hydroxypropylation. The hydroxypropylated starch paste had a planar structure. The procedure used to prepare dual-modified starches also affected the product properties. Cross-linking reduced the degree of subsequent hydroxypropylation, but hydroxypropylation increased the degree of subsequent cross-linking. The results indicate that hydroxypropylation of rice starch took place inside starch granules.
A-I. Yeh and S-L. Yeh, Cereal Chemistry 70 (1993) 596-601

B1212 – Kinetics of phase transition of native, cross-linked, and hydroxypropylated rice starches.

Kinetics of the phase transition of native and chemically modified rice starches have been investigated by using differential scanning calorimetry (DSC) after isothermal treatment. At the experimental conditions, the phase transition of these starches followed pseudo-first order kinetics. The kinetic order was not affected by the two chemical modifications used, hydroxypropylation and cross-linking, while the rate constants were altered. From the Arrhenius plot, peak temperature (T[p]) from DSC thermogram appeared to be the turning point for the two steps, swelling and disruption/dissolution, associated in the phase transition of starch granules. When the temperature was below T[p], high activation energy was obtained and fell in the range of 61 to 75kcal/mol. Once the temperature was above T[p], the activation energy dropped to be in the range of 10 to 30kcal/mol and the starch became less temperature sensitive.
A-I. Yeh and J-Y. Li, Starch/Stärke 48 (1996) 17-21

B1174 – Crystallisation and melting behaviour of poly (3-hydroxybutyrate) in dilute solution : towards an understanding of physical gels

The purpose of this paper is to examine the thermodynamics of physical gelation by presenting some results gathered on gels of stereo-regular poly hydroxybutyrate (PHB). The investigation has been carried out in dilute solutions mainly by high sensitivity scanning calorimetry through the use of two solvent systems. Gels were formed under several different experimental conditions to clarify the thermo-reversibility of the gelation-dissolution process. Some peculiarities of the polymeric features in the gel phase are discussed in view of the recent assessment of the implication of chain stiffness as the triggering factor for gelation versus crystallisation.
D. Fabri, J. Guan, A. Cesaro, Thermochimica Acta 321 (1998) 3-16

B1163 – Calorimetric characterization of different yeast strains in doughs.

In this work microbial growth and metabolism of Saccharomyces cerevisiae from three different strains in a bread dough system were investigated by means of SETARAM C80D twin calorimeter in isothermal conditions at various temperatures. The overall calorimetric signal accounts for two main contributions, namely oxidative and anaerobic degradation of substrate. Parallel measurements of the biomass growth N(t), the substrate (maltose) consumption, fermentation gases (CO2) production, dough volume increase, were also performed. Differences were observed between the three yeasts both in the metabolic energetics and growth and metabolism kinetics.
M. Riva, D. Fessas, L. Franzetti, A. Schiraldi, Journal of Thermal Analysis and Calorimetry 52 (1998) p 753-764

B1145 – Gelation properties of deamidated soluble wheat proteins.

Compared with native wheat gluten proteins, chemically modified deamidated gluten proteins are more readily dispersed in aqueous solution. In this paper the gelation behaviour of commercial deamidated gluten, commonly referred to as soluble wheat protein (SWP) on heating as well as its interaction with calcium and basic proteins was investigated. Soluble wheat protein decreased in viscosity on heating at 60°C due to the breakdown of protein aggregates which was observed by phase contrast microscopy. Heating to 60°C was accompanied by an increase in hydrophobicity without conformational transitions as observed by differential scanning calorimetry. In aqueous solutions at concentrations greater than 17% w/w and after autoclaving at 120°C, SWP produced firm gels which were examined by large deformation testing. In the presence of calcium strong but coarse gels were formed which exhibited syneresis. The addition of 0.1-0.5% w/w of basic lysozyme or clupeine to the highly negatively charged SWP induced gelation at the lower temperature of 80°C which was detected by small deformation rheological testing and microscopy using basic and acidic stains. The structure and mechanism of lysozyme-induced gelation of SWP is different from the high thermal (>100°C) gelation of SWP alone. In the lysozyme-induced gelation non-covalent mainly electrostatic interactions occur between the positively charged lysozyme and the negatively charged soluble wheat proteins with the absence of conformational changes in the SWP. In contrast, in the heat gelation of SWP proteins at 120°C it is proposed that the intradisulphide bonds are broken leading to conformational changes and subsequent association and gelation. This mechanism is supported by the fact that gelation occurred spontaneously in the presence of urea and beta-mercaptoethanol indicating that in SWP the disulphide bonds normally prevent gelation unless exposed to very high heat (120°C) or disulphide reducing reagents.
G.L. Friedli, N. Howell, Food Hydrocolloids 10 (1996) 255-261

B1111 – Thermal properties of polysaccharides at low moisture. II. Molecular order and control of dissolution temperature in agar

Differential scanning calorimetry (DSC) has been used to probe ordered structures and glassing behaviour for a range of agars containing < 25% w/w water. Most commercial agars are supplied in an ordered (double-helical) state, show an endothermic helix-to-coil transition above 100C at low-moisture, and require 90-100C for solubilisation in excess water. Agars dried from the coil (single-chain) state show no corresponding endothermic transitions and only require a minimum of 45C for aqueous dissolution. Evidence from helix-to-coil transition enthalpies, equilibrium water content as a function of relative humidity, and solid-state13C NMR spectroscopy suggests that water molecules are associated enthalpically with double-helical agar. Single-chain agar is apparently not obtained in a glassy state by direct drying from solution, but in common with double-helical forms, exhibits rubber/glass transition behaviour following heating (in a DSC pan) to 180C.
D. Cooke, M.J. Gidley, N.D. Hedges, Journal of Thermal Analysis 47 (1996) 1485-1498

B1105 – Vitrification of trehalose by water loss from its crystalline dihydrate.

Trehalose dihydrate, on careful dehydration below its fusion point, retains its original crystal facets but becomes X-ray amorphous, an unusual example of direct crystal-to-glass transformation. From DSC studies, the glass obtained by this route seems to be of abnormally low enthalpy, but after an initial scan, the normal form of glass transition is exhibited, withT g=115C, a higher value than previously reported. We give a preliminary thermal and mechanical characterization of this material and find it to be a very fragile liquid. The highT g is shown to rationalize the exceptionally high water content of the trehalose+water solution that vitrifies at ambient temperature (i.e.T g=298 K), and hence helps explain its use by Nature as a desiccation protectant. The spontaneous vitrification of crystalline materials during desolvation is related to the phenomenology of pressure-induced or decompression-induced vitrification of crystals via the concept of limiting metastability.
S-P. Ding, J. Fan, J.L. Green, Q. Lu, E. Sanchez, C.A. Angell, Journal of Thermal Analysis 47 (1996) 1391-1405

B1104 – Thermal transitions of cassava starch at intermediate water contents.

Order-disorder transitions were investigated in native cassava starch at intermediate moisture contents (35 to 60% wt. water), using Differential Scanning Calorimetry (DSC) and dynamic Wide Angle X-ray Diffractometry (WAXS) with a synchrotron radiation source. The gelatinization of granules occurs as a cooperative process, due to constraints induced in crystallites by the amorphous areas. Variations of water content (water volume fraction from 0.28 to 0.86) and heating rate (0.2-10°C min-1) allowed access to equilibrium melting conditions. Cassava starch exhibits a higher melting temperature of the undiluted starch (T m o ) and an equivalent melting enthalpy of the repeating glucosyl unit (H u), compared to other A-type starches. At intermediate water content (45% wt. water), a two-stage melting process is evidenced, with different kinetic rates below and above 75°C.
V. Garcia, P. Colonna, D. Lourdin, A. Buleon, H. Bizot, M. Ollivon, Journal of Thermal Analysis 47 (1996) 1213-1228

B1103 – Construction of a wheat-flour state diagram. Application to extrusion processing.

We use pressure-variable differential scanning calorimetry to detect and characterize thermally induced transitions (glass, melting, gelatinization) in pre- and post-extruded wheat flour. The resulting data allow us to construct a two-dimensional state diagram which maps the physical states that pre- and post-extruded wheat flour can assume, at constant pressure, as a function of moisture content, temperature, and the specific mechanical energy, SME, generated in the extruder. We describe how this state diagram can be used to map the path of extrusion processing, to assess the impact of extrusion conditions, and, ultimately, to design formulations and processing conditions that result in desired end-product attributes. For the extrudates, we find that the extent of processing-induced fragmentation, as monitored by reductions in the extrudate glass transition temperature,T g, increases with the SME generated in the extruder. We demonstrate that a wheat-flour state diagram, which includes the glass curve of the wheat-flour extrudates produced at various SME values, allows one to predict and control the impact of processing conditions on extrudate properties.
G. Kaletunc, K.J. Breslauer, Journal of Thermal Analysis 47 (1996) 1267-1288

B1102 – A calorimetric study of egg white proteins.

Egg white is of great interest for many culinary and industrial applications. Egg white is used for coating, gluing, thickening and so on in pasta, desserts, etc. There is thus a great interest from the industrial point of view to better know this raw material, used in very large amounts in the dessert production for example, and to obtain egg white fractions with different functional properties. Various egg white fractions prepared by selected procedures were analyzed by differential scanning calorimetry (DSC). The products resulting from a given fractionation procedure can thus be described by the thermal denaturation parameters (temperatures and enthalpies) of the egg white proteins. This work demonstrates the interest of the DSC technique and proves that the fractionation procedures selected here give the expected protein fractions.
M. Ferreira, C. Hofer, A. Raemy, Journal of Thermal Analysis 48 (1997) 683-690

B1092 – Application of differential scanning calorimetry in food research and food quality assurance.

Differential scanning calorimetry (DSC) is the most widely used thermal analytical technique in food research and it has a great utility in quality assurance of food. Proteins are the most studied food components by thermal analysis including studies on conformation changes of food proteins as affected by various environmental factors, thermal denaturation of tissue proteins, food enzymes and enzyme preparations for the food industry, as well as effects of various additives on their thermal properties. Freezing-induced denaturation of food proteins and the effect of cryoprotectants are also monitored by DSC. Polymer characterization based on DSC of polysaccharides, gelatinization behaviour of starches and interaction of starch with other food components can be determined, and phase transitions during baking processes can be studied by DSC. Studies on crystallization and melting behaviour of fats observed by DSC indicate changes in lipid composition or help characterizing products. Thermal oxidative decomposition of edible oils examined by DSC can be used for predicting oil stability. Using DSC in the freezing range has a great potential for measuring and modelling frozen food thermal properties, and to estimate the state of water in foods and food ingredients. Research in food microbiology utilizes DSC in better understanding thermoadaptive mechanisms or heat killing of food-borne microorganisms. Isothermic microcalorimetric techniques provide informative data regarding microbial growth and microbial metabolism.
J. Fakas, C. Mohacsi-Farkas, Journal of Thermal Analysis 47 (1996) 1787-1803

B1083 – DSC and EPR investigation of the effect of fat crystallization on the consistency of butter.

It was possible to determine the liquid fat content and melting behaviour of butters unenriched and enriched in low melting point milk fat fraction (mp=10C) made from traditionally (6-11-11C) and heat step technology ripened (6-20-11C) cream by using EPR spectroscopy and ultrasensitive DSC methods. It was determined that - butters made from heat step technology (H) ripened cream have smaller liquid fat content in the continuous fat phase than that of made from traditionally (K) ripened cream. - there were different fat melting behaviours: the K-butter in temperature range of 0-20C had one melting peak while H-butter had two ones, and - the effect of enrichment is different in the fraction of low melting point: the melting temperature decreased in the case of K-butter, but the H-butter exhibited smaller enthalpy at the lower melting temperature having same melting temperatures. Our experiments support the view that H-butter is much more structured than K-butter which is caused by fat fragments containing cubic crystals, developed during the ripening of heat step technology. With respect to the minimum liquid fat content of maximum fat fragments, and vice versa, the cream ripening temperature of solid and spreadable butter can be optimalized by determination of cream ripening temperature-liquid fat content function (min.-max. curve) The experiments have proved without any doubt that butter of cold spreadable, not softening at room temerature, can be only produced by the combination of heat step cream ripening and enrichment with a low melting point fraction.
B. Schäffer, D. Lörinczy, S. Szakaly, Journal of Thermal Analysis 47 (1996) 515-524

B1060 – Compatibility of some tropical hardwoods species with portland cement using isothermal calorimetry

L. Franzetti, A. Galli, A. Perazzoli, M. Riva, Annali di Microbiologia ed Enzimologia 45 (1995) 291-300

B1058 – Bread staling : A Calorimetric approach.

Simple recipe breads with different water contents were allowed to stale in well-defined conditions. Bread crumb was investigated using differential scanning calorimetry, thermogravimetry analysis (TGA), and stress-strain determinations. Calorimetric investigations extended to subambient temperature allowed an exothermic signal to be recognized just about room temperature that appeared partially reversible on repeated heating-cooling cycles across the -10 to 35°C range. The corresponding thermal effect was maximum after aging 8-10 hr. According to the TGA investigations, the release of water on heating revealed two main binding states : water-1 and water-2. The relevant fractions were bread-age dependent ; water-1 reached a minimum after aging 8-10 hr at room temperature, while the overall water content remained practically unchanged. These findings suggested a model for the extension of a crosslink network throughout the bread crumb. Water molecules would be displaced along polymer chains acting as sliders of an interchain zipper. The consequent direct interchain crosslinks would allow formation of a network that would justify the increasing firmness of the crumb. The same mechanism would also sustain the growth of amylopectin crystals. Accordingly, the observed correlation between starch retrogradation (evaluated from the endothermic effect of amylopectin fusion) and increased crumb firmness should be reconsidered in the frame of a more general picture where water molecules play a key role in the definition of the product structure.
A. Schiraldi, L. Piazza, M. Riva, Cereal Chemistry 73 (1996) 32-39

B1057 – Glass transitions of extrudates : relationship with processing-induced fragmentation and end-product attributes.

We used differential scanning calorimetry to measure glass transition temperatures (Tg) for two types of corn-flour extrudates that differed primarily in their amylose-to-amylopectin ratios. Our experiments were designed so that extrusion-induced fragmentation represented the primary cause of changes in Tg. We found that the extent of fragmentation, as monitored by reductions in the Tg of the extrudates, increased with the specific mechanical energy generated in the extruder. Further, the Tg of the extrudate decreased rapidly with increases in moisture content, thereby demonstrating that the glass phase of the extrudate is sensitive to the relative humidity of the storage environment. The Tg values of the extrudates also related to crispness and denseness, two important sensory-textural properties. Based on these results, we propose the use of Tg measurements on extrudates as a criterion for adjusting extruder operating conditions to produce extrudates with optimal textural properties, as well as to select optimum storage conditions (temperature and relative humidity) to improve stability and shelf life of extruded products.
G. Kaletunc and K.J. Breslauer, Cereal Chemistry 70 (1993) 548-552

B1056 – Effect of sucrose on the structure, mechanical strength and thermal properties of corn extrudates.

The effects of sucrose on extrusion process parameters and the structural, mechanical and thermal characteristics of the resultant extrudates have been investigated. To this end, sucrose in concentrations between 0 and 10% by weight was added to corn meal prior to extrusion at two levels of moisture (15 and 20%). The resulting data revealed the following significant features. (i) At the higher moisture level, sucrose progressively reduced the specific mechanical energy, while exhibiting little effect at the lower moisture level. (ii) At both moisture levels, sucrose increased the bulk density and reduced the cell size; this effect was progressive for high extrusion moisture samples and evident only at high sucrose contents for low extrusion moisture samples. (iii) In extrudate samples equilibrated to moisture contents between 12 and 17% wt, sucrose progressively plasticized the structures, as assessed by compression, dynamic mechanical spectrometry, and differential scanning calorimetry. In the aggregate, these results showed that the addition of sucrose requires a modification of the extrusion operating conditions to produce extrudates with optimal textural and storage properties.
A. Barrett, G. Kaletunç, S. Rosenburg and K. Breslauer, Carbohydrate Polymers 26 (1995) 261-269

B1035 – Growth and metabolism parameterization of lactic bacteria in the production of yogurt : an isothermal calorimetry approach

M. Riva, A. Schiraldi, G. Med Cat (1995) 283-286

B1033 – Effects of salts on the gel-sol transition of gellan gum by differential scanning calorimetry and thermal scanning rheology

The rheological and thermal properties of sodium form gellan gum solutions with and without sodium chloride, potassium chloride, calcium chloride and magnesium chloride were studied by dynamic viscoelastic measurement and differential scanning calorimetry. Temperature dependence of the loss modulus for gellan gum solutions of lower concentrations without salt showed a one step-like change at a certain temperature, however that for concentrated gellan gum solutions (>2.0%) showed two step-like changes. The higher temperature process Thc may be attributed to the helix-coil transition and found in between the exothermic and endothermic peak temperatures Ts and Tm observed in cooling and heating DSC curves, while the lower temperature process Tsg may be attributed to the sol-gel transition. Temperature dependence for gellan gum solutions of higher concentrations (>3.2%) showed a large hysteresis, moreover, the temperature at which the loss shear modulus G? showed the second step decrease shifted to higher temperatures with increasing concentration of gellan gum. The cooling or heating DSC curves for gellan gum solutions of lower concentrations showed a single exothermic or endothermic peak, and both exothermic peak temperature Ts and endothermic peak temperature Tm shifted to higher temperatures, and both exothermic and endothermic enthalpies increased with increasing concentration of gellan gum. However, for a gellan gum solution of a concentration higher than 3.2%, the endothermic peak in the heating DSC curve split into two peaks, while the cooling curve showed only one endothermic peak. The lower temperature endothermic peak in the heating DSC curve corresponds with the first step decrease of G? in the heating process of rheological measurement, and the higher temperature endothermic peak corresponds with the second step decrease of G?. The viscoelastic change of gellan gum solutions was more remarkable by the addition of K+ than Na+, and by Ca2+ than by Mg2+. The viscoelastic behavior of gellan gum solutions was influenced much more strongly by divalent cations than by monovalent cations. DSC cooling curves of gellan gum solutions showed a single exothermic peak shifting to progressively higher temperatures with increasing concentration of monovalent cations. At low concentration of monovalent cations, the DSC heating curves showed a single endothermic peak, however, with more progressive addition of salt, the endothermic peak gradually developed bimodal character and eventually split into multiple peaks. With increasing concentration of divalent cations, the exothermic and endothermic enthalpies estimated for a main peak increased up to a certain concentration and then decreased. Moreover, the endothermic peaks in the presence of sufficient salts were too broad to be resolved from the baseline, and many other peaks were observed at higher temperatures. Gellan gum solutions with sufficient divalent cations form firm gels on cooling to below the setting temperature, and then it was difficult to remelt them, which was quite different from the behavior of thermoreversible gels formed in the presence of monovalent cations.
E. Miyoshi, T. Takaya, K. Nishinari, Thermochimica Acta 267 (1995) 269-287

B0981 – A DSC investigation of the effects of heating rate on cooking indexes of ground meat

M. Riva, A. Schiraldi, Italian Journal of Food Science 6 (1994) 43-58

B0958 – Investigation of protein-containing food-industrial products by DSC method

(1) + benzene (2) + 1-chlorobutane (3). A Redlich-Kister type of equation was used
D. Lörinczy, B. Nagy, J. Kispéter

B0957 – Solubility of vegetable cuticular waxes in supercritical CO2 isothermal calorimetry investigations

to represent and correlate the results.
A. Stassi, A. Schiraldi, Thermochimica Acta 246 (1994) 417-425

B0956 – Characterization of rice cooking : isothermal differential scanning calorimetry investigations

Isothermal calorimetry allows rice cooking to be simulated directly at various temperatures in excess water. The signal can be interpreted as the sum of the thermal effect of the starch gelatinization, which obeys first-order kinetics, and of a further process that can be tentatively related to water diffusion. This effect is greatly reduced in ground rice, as revealed by comparing the behaviour of whole and ground rice samples. Determinations of water uptake seem to confirm this hypothesis. The enthalpy of gelatinization drawn from these data can be matched with that from non-isothermal DSC investigations carried out at low heating rate (<0.5°C min-1).Analogous results and conclusions can be drawn from non-isothermal DSC investigations carried out on partially pregelatinized samples.
M. Riva, A. Schiraldi, L. Piazza, Thermochimica Acta 246 (1994) 317-328

B0890 – Kinetic parameterization of transitions and reactions in food systems from isothermal and non-isothermal DSC traces

When reactions and/or transitions take place within a food system, i.e. in the presence of a number of components, their kinetic parameterization can be approached by careful analysis of isothermal DSC traces. Even when the signal is relatively smooth, a
M. Riva and A. Schiraldi, Thermochimica Acta 220 (1993) 117-130

B0883 – Synergistic interaction of xanthan gum with glucomannans and galactomannans

P.A. Williams, D.H. Day, M.J. Langdon, G.O. Phillips and K. Nishinari, Food Hydrocolloids 4 (1991) 489-493

B0878 – Precise determination of low level sucrose amorphism by microcalorimetry

The DSC curve of freeze-dried amorphous sucrose shows the glass transition, the crystallization and the melting (just before decomposition) of the sample. Sucrose crystallization occurs below 100°C this phenomenon can therefore be observed with the microcalorimeter Setaram Micro-DSC used in the scanning mode. Mixtures of amorphous and crystalline sucrose in known proportions were used to calibrate the instrument. Low level amorphism (down to about 0.5%) could be detected and quantitatively evaluated on the basis of the crystallization enthalpies determined. The calibration curve obtained can be applied to determine the degree of amorphism in milled sucrose. A simple gravimetric method, based on the desorption of water induced by recrystallization of the amorphous layer can be used to obtain similar data more rapidly. This simple method is particularly useful for controlling the amorphism on line during a process, and is also briefly described.
A. Raemy, C. Kaabi, E. Ernst, G. Vuataz, Journal of Thermal Analysis 40 (1993) 437-444

B0835 – Studies on the synergistic interaction of konjac mannan and locust bean gum with kappa carrageenan

P.A. Williams, S.M. Clegg, M.J. Langdon, K. Nishinari, G.O. Phillips, Gums and Stabilisers for the Food Industry 6 (1992) 209-216

B0819 – Microcoagulation of a whey protein isolate by extrusion cooking at acid pH

A whey protein isolate (WPI) was coagulated by thermomechanical processing in a twin screw extruder. Nonaggregated semi-solid spreads were obtained only in the pH range 3.5-3.9, at ca 20% protein, a barrel temperature of 90-100[o]C. WPI extrusion-coagulated at pH 3.9 displayed a high nitrogen solubility (NSI). Electrophoresis indicated that the beta-lactoglobulin constituent was entirely soluble in 1% SDS, while scanning calorimetry revealed protein unfolding. WPI extrusion-coagulated at pH 4.5-6.8 displayed lower NSI, were less soluble in 1% SDS, were unfolded and had grainy texture
C. Queguiner, E. Dumay, C. Salou-Cavalier, J.C. Cheftel, Journal of food science 57 (1992) 610-616

B0818 – DSC study of melting and glass transition in gelatins

In the range from -50° to +130°C, the temperature dependence of the heat capacity for different kinds of gelatins with water contents of from 2 to 95% was studied by the DSC method. It was shown that, in all studied cases, metastable collagen-like structures are formed in gels or crystalline gelatins, with thermodynamic parameters depending on the formation conditions. The characteristic properties of the glass transitions in amorphous gelatins and crystalline gelatins with different melting heats and different contents of the ordered phase were established. Special attention is paid to the structural properties of free and bound water. The dependence of the glass transition temperatureT g on the bound water content was shown to be of general applicability for many denatured biopolymers. Free water in gelatins, in distinction to the bound water, does not act as a plasticizer, but forms a rigid matrix inhibiting the glass transition.
G.I. Tseretely, O.I. Smirnova, Journal of Thermal Analysis 38 (1992) 1189-1201

B0814 – Effects of potassium chloride and sodium chloride on the thermal properties of gellan gum gels

H. Moritaka, K. Nishinari, N. Nakahama, H. Fukura, Biosci. Biotech. Biochem. 56 (1992) 595-599

B0808 – Conformation and physical properties of the bacterial polysaccharides gellan, welan, and rhamsan

G. Robinson, C.E. Manning, E.R. Morris, Food polymers gels & colloids (1991) 22-33

B0807 – Mixed gels formed with konjac mannan and xanthan gums

P.A. Williams, S.M. Clegg, D.H. Day, G.O. Phillips, Food polymers, gels and colloids (1991) 339-348

B0760 – Starch gelatinization in pasta cooking: differential flux calorimetry investigations

Pasta cooking conditions were simulated in a differential flux calorimeter. The profile of the endothermic starch gelatinization peak was observed to directly describe the process according to first-order kinetics. An early small exothermic effect was attributed to wetting. Isothermal calorimetry provided much more reliable results than do other traditional approaches, and it allows comparison among different kinds of pasta. This work gives a detailed presentation of the physical meaning underlying the calorimetric trace, which allows assessment of the gelatinization kinetics and simple thermodynamic treatment.
M. Riva, L. Piazza and A. Schiraldi, Cereal Cemistry 68 (1991) 622-627

B0655 – Mesures des capacités calorifiques d’émulsions eau dans huile.

D. Clausse, S. Hassam, M. Bouzoubaa, AFCAT (1990) 49-56

B0624 – Mise en évidence de la rétrogradation de l’amidon par microcalorimétrie isotherme.

A. Raemy, C. Kaabi, W.M. Maclnnes, JCAT (1990)

B0575 – A calorimetric, NMR and X-Ray diffraction study of the melting behavior of tripalmitin and tristearin and their mixing behavior with triolein

I.T. Norton, C.D. Lee-Tuffnell, S. Ablett, S.M. Bociek, Journal of the American Oil Chemists' Society 62 (1985) 1237-1244

B0514 – Oxidation of lipids studied by isothermal heat flux calorimetry

The exothermic reaction of the autoxidation of lipids has been studied by isothermal heat flux calorimetry at temperatures between 80°C and 160°C. A number of lipid samples have been kept in the calorimeter under excess of oxygen for 1 or 2 hours. The capabilities of the method are illustrated by examples exhibiting different thermal behaviour, where the influence of temperature and the role of unsaturation and of antioxidants are presented for selected lipids.
A. Raemy, I. Froelicher and J. Loeliger, Thermochimica Acta 114 (1987) 159-164

B0447 – Thermal analysis and safety in relation to food processing

The adaptation of thermal analysis techniques to study exothermic phenomena and self-ignition of foodstuffs, and the use of special tools to simulate and analyze dust explosions are described. The examples shown should provide a better understanding of the mechanisms involved in phenomena which can lead to the bursting of an autoclave, to fires or to dust explosions during food processing operations.
A. Raemy, P. Lambelet and J. Loeliger, Thermochimico Acta 95 (1985) 441-446

B0426 – Etude du comportement thermique des aliments par analyse thermique différentielle et calorimétrie différentielle programmée.

A. Raemy, F. Michel, P. Lambelet, Calorimétrie et Analyse thermique 15 (1984) 11-18

B0417 – A calorimetric study of self-heating in coffee and chicory

A. Raemy, P. Lambelet, J. Fd. Technol. 17 (1982) 451-460

B0416 – Thermal behaviour of carbohydrates studied by heat flow calorimetry

The technique of heat flow calorimetry was used to study the thermal behaviour of different carbohydrates between 20°C and 270°C The samples were analyzed by heating in sealed cells. The temperature range in which exothermic reactions, due to thermal decomposition, occurred varied widely depending on the type of carbohydrate investigated. Reaction enthalpies of 44 sugars and polysaccharides are given. Endothermic phenomena, such as fusion or vaporization of crystallized water, were also observed: fusion temperatures and enthalpies of 34 sugars and sugar alcohols are listed. Calorimetric curves showing crystallization of amorphous sucrose, cellobiose end lactose are also presented.
A. Raemy and T.F. Schweizer, Journal of Thermal Analysis 28 (1983) 95-108

B0415 – Thermal behaviour of milk powders studied by differential thermal analysis and heat flow calorimetry

The technique of heat flow calorimetry was used to study the thermal behaviour of different milk powders above 20°C. Exothermic reactions of different types occurred when measurements were made with the samples in sealed cells. According to our interpretation of the calorimetric curves, these reactions correspond to: crystallization of amorphous lactose, Maillard reaction between milk proteins and lactose, oxidation of milk fat and decomposition of lactose. Their relative importance is discussed. In addition, the technique of high-pressure differential thermal analysis was used for studying spontaneous ignition and combustion of milk powders, under a large oxygen excess. The role of fat, carbohydrate and protein decomposition is underlined. Some self-ignition temperature values are given.
A. Raemy, R.F. Hurrell and J. Löliger, Thermochimica Acta 65 (1983) 81-92

B0340 – DSC-Untersuchungen an stärken

Von K. Eberstein, R. Höpcke, G. Konieczny-Janda, R. Stute, Starch/Stärke 32 (1980) 397-404

B0324 – Thermal behavior of cereals studied by heat flow calorimetry

Heat flow calorimetry was used for studying the thermal behavior of cereals above 20 C. When the samples were heated in sealed measuring cells, intense exothermic reactions were observed at about 170 C. These exothermic reactions, which are associated with roasting and carbonization of the foods, were mainly attributed to carbohydrates.
A. Raemy and J. Loliger, Cereal Chemistry 59 (1982) 189-191

A1621 – Osmo-dehydration of apple pulp studied by means of classical and Knudsen thermogravimetric approach

Classical thermogravimetry and its modification with Knudsen cells were employed to quantitatively investigate the osmo-dehydration of apple pulp samples. The data allowed realization of the complex mechanism of the process, which is not a mere solvent depletion, since it also implies sugar exchanges between the apple tissue and the hypertonic syrup used to dehydrate the fruit. The comparison between different hypertonic syrups, all at the same water activity, showed that maltose is more effective than either sucrose or a mixture of sugars that mimics the saccharide content of the apple. The conclusions are supported by a thermodynamic analysis of the aqueous solutions of these sugars at a concentration level as large as that of the hypertonic syrups used for the osmo-dehydration process.
Paola Pani, Marco Signorelli, Alberto Schiraldi, Danila Torreggiani, J Therm Anal Calorim (2010) 102, 383–390

A1391 – Water properties in wheat flour dough II: classical and knudsen thermogravimetry approach

Thermo-Gravimetric Analysis (TGA) investigations suggest that water in a wheat flour dough is partitioned in various states related to the different disperse phases of the system. Classical TGA results indicate the gross water partition at the macroscopic level, while Knudsen TGA investigations, that allow evaluation of the relative humidity of the dough at room temperature, suggest the involvement of water in the structure of the dough at a supra-molecular level. The overall moisture content, the mechanical stresses and the presence of extra non-starch polysaccharides and/or soluble proteins, can affect this partition, either promoting water displacements across the inter-phases, or modifying the supra-molecular structure of the system. The investigations, extended to bread crumb during ageing, indicate that water undergoes displacements and forms stronger links with the components of the aged crumb with a kinetic law that can be influenced by the presence of extra non-starch polysaccharides.
Dimitrios Fessas, Alberto Schiraldi, Food Chemistry 90 (2005) 61–68

A1389 – Classical and Knudsen thermogravimetry to check states and displacements of water in food systems

Water states and displacements can be investigated with thermogravimetry (TG) either in its classical or in the Knudsen version (where standard pans are replaced with Knudsen cells). The case of wheat flour dough is considered in various steps of bread making, namely, mixing, proofing, baking, staling. The split of DTG signals into various components (gaussian functions) support the assumption that the overall dough water is partitioned into various fractions. Few comments are devoted to water displacements during freezing.
A. Schiraldi, D. Fessas, Journal of Thermal Analysis and Calorimetry, Vol. 71 (2003) 221–231

A1371 – Water properties in wheat ¯our dough. I: Classical thermogravimetry approach

Thermogravimetric analysis allowed inspection of the behavior of water within a wheat ¯our dough. In such a system water is partitioned between coexisting phases which are none the less far from the true thermodynamic equilibrium. The vaporization rate revealed that water is released in two main steps, the ®rst corresponding to a mere di€usion process, the second being instead related to the desorption of water more tightly bound to the gluten network. It was observed that the overall dough moisture, the extent of mixing, the dough resting time after mixing can modify water partition between phases and the way water is released during the temperature scan. Some e€ect was also recognized in dough samples to which original water soluble proteins had been added
Dimitrios Fessas, Alberto Schiraldi, Food Chemistry 72 (2001) 237-244

A1202 – Kinetics of the pyrolysis and combustion of olive oil solid waste

The pyrolysis and combustion of solid residues from olive oil processing were studied by dynamic TG-DTG at heating rates between 5 and 20°Cmin-1 at atmospheric pressure. Two different atmospheres were used: on the one hand, an inert atmosphere (He) in order to study the pyrolysis of the material, and on the other hand an oxidative atmosphere (He:O2 in different ratios) to study its combustion. Pyrolysis follows a two parallel and independent fractions model, with kinetic parameters typical of holocelulose (12%) and lignin (48%). Combustion adds a third reaction to the model, which is cocurrent, due to the combustion does not start until the main devolatilization is finished, attaining kinetic parameters and reaction orders typical of a gasification reaction.
J. Jauhiainen, J.A. Conesa, R. Font, I. Martin-Gullon, J. Anal. Appl. Pyrolysis 72 (2004) 9-15

A1141 – The prediction of the characteristics of some polysaccharides from molecular modeling. Comparison with effective behavior

Molecular modeling is a convenient technique to predict the behavior of polymers in solution as well as in the solid state; also, interaction with water and other small molecules can be examined. In our presentation, the main techniques used for molecular modeling of polysaccharides are briefly recalled and applied to different systems for which the chemical structure is known (allowing valuable description of the molecule). Then, experimental determination of the local conformation byNMRor of the global dimensions of galactomannan and chitosan chains by light scattering are compared with the corresponding predicted parameters with good agreement; interaction of amylose with water is studied by thermogravimetry and DSC and strongly interacting water are localized by molecular modeling. At end, modeling of crystalline and amorphous solids together with surface interactions is presented. For the first time, this paper demonstrates from a series of data obtained in our laboratory the validity of the molecular modeling approach proposed to predict the behaviour of polysaccharides in solution or solid state.
K. Mazeau, M. Rinaudo, Food Hydrocolloids 18 (2004) 885-898

A1030 – Water – an important parameter for the preparation and proper use of certified reference materials

Property values of powdered certified reference materials (CRMs) are very often related to dry mass. The dry mass is indirectly determined by measuring the moisture content of the sample. The most commonly used methods are the drying oven method and the Karl Fischer titration (KFT). It is well known that these two methods may give different values for the moisture/water content. In this study thermogravimetry was used to simulate the drying oven method and to investigate the reasons of the differences between both moisture/water content determination methods. A mass spectrometer coupled to a thermobalance (TGMS) added further useful information regarding the release of volatile substances and the decomposition of the material during the drying process. The relative humidity of the laboratory may influence the water content of powdered CRMs because of their more or less pronounced tendency to take up water (hygroscopicity). This fact can lead to biased property values. The water adsorption kinetics and the water uptake capacity vary, depending on the constitution of the sample. This was studied analysing several powdered food CRMs and individual constituents thereof. The speed of water uptake and the water uptake capacity were described using an exponential function. The findings have consequences both for the producer and for the user of certified reference materials.
S. Yazgan, A. Bernreuther, F. Ulberth, H-D. Isengard, Food Chemistry 96 (2006) 411-417

A0531 – Scaffolds for bone restoration from cuttlefish

Scaffolds of pure hydroxyapatite suitable for either direct clinical use or tissue-engineering applications were successfully produced via hydrothermal transformation of aragonite, obtained from fresh cuttlefish bones, at 200°C followed by sintering. Beyond low production cost, worldwide availability and natural-biological origin of raw materials, the produced scaffolds have ideal pore size and interconnectivity features suitable for supporting biological activities, such as bone tissue growth and vascularization. Bioactivity in vitro tests were excellent: (a) rapid and pronounced formation of hydroxyapatite occurred when the scaffolds were immersed in simulated body fluid (SBF), and (b) outstanding proliferation of osteoblasts was registered. The produced scaffolds can be machined and shaped very easily at any stage of processing. Therefore, these ceramic scaffolds can satisfy both bioactivity demands and the requirements for shaping of tailor-made individualized implants, especially for randomly damaged bones.
J.H.G. Rocha, A.F. Lemos, S. Agathopoulos, P. Valério, S. Kannan, F.N. Oktar, J.M.F. Ferreira, Bone 37 (2005) 850-857