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Starch Gels (starch + gel)

Distribution by Scientific Domains
Chemistry85%

Terms modified by Starch Gels

  • starch gel electrophoresis
    		•

    Selected Abstracts

    MOISTURE SORPTION CHARACTERISTICS of STARCH GELS.

    JOURNAL OF FOOD PROCESS ENGINEERING, Issue 3 2004
    PART II: THERMODYNAMIC PROPERTIES
    ABSTRACT A thermodynamic approach was used to interpret the experimental adsorption and desorption isotherm data for potato starch gel. Calculation of the thermodynamic properties (differential enthalpy, integral enthalpy, differential entropy and integral entropy) provides an understanding of the properties of water and energy requirements associated with the sorption behavior. Isosteric heats (differential enthalpies) were calculated through direct use of moisture isotherms by applying the Clausius-Clapeyron equation. the differential enthalpy and entropy decreased with increasing moisture content and were adequately characterized by an exponential model. A plot of differential heat versus entropy satisfied the enthalpy-entropy compensation theory. the spreading pressure increased with increasing water activity, and decreased with increasing temperature. the net integral enthalpy increased with moisture content to a maximum value (around the monolayer moisture content) and then decreased. In a reverse manner, the net integral entropy decreased with moisture content to a minimum value and then increased. [source]

    Influence of Cooling Rate on Glass Transition Temperature of Sucrose Solutions and Rice Starch Gel

    JOURNAL OF FOOD SCIENCE, Issue 6 2003
    C.-L. Hsu
    ABSTRACT: The study's objectives were to determine the influence of cooling rate through the primary zone of freezing on Tg in sucrose solutions and rice starch gels. The influence of cooling rate, water content, and annealing on Tg were evaluated. Results indicated that the observed Tg values for sucrose solutions were lower after rapid cooling (70% solids: rapid cooling ,66.7°C; slow cooling ,64.6 °C; 30% solids: rapid cooling ,34.6 °C; slow cooling ,33.3 °C). The Tg values of annealed samples are higher than the Tg of both rapidly and slowly cooled samples (70%: ,44.2 °C; 30%: ,32.7 °C). The Tg of the rice starch gel was ,9.0 °C after rapid cooling and ,7.5 °C after slow cooling. [source]

    MOISTURE SORPTION CHARACTERISTICS of STARCH GELS.

    JOURNAL OF FOOD PROCESS ENGINEERING, Issue 3 2004
    PART II: THERMODYNAMIC PROPERTIES
    ABSTRACT A thermodynamic approach was used to interpret the experimental adsorption and desorption isotherm data for potato starch gel. Calculation of the thermodynamic properties (differential enthalpy, integral enthalpy, differential entropy and integral entropy) provides an understanding of the properties of water and energy requirements associated with the sorption behavior. Isosteric heats (differential enthalpies) were calculated through direct use of moisture isotherms by applying the Clausius-Clapeyron equation. the differential enthalpy and entropy decreased with increasing moisture content and were adequately characterized by an exponential model. A plot of differential heat versus entropy satisfied the enthalpy-entropy compensation theory. the spreading pressure increased with increasing water activity, and decreased with increasing temperature. the net integral enthalpy increased with moisture content to a maximum value (around the monolayer moisture content) and then decreased. In a reverse manner, the net integral entropy decreased with moisture content to a minimum value and then increased. [source]

    Influence of Cooling Rate on Glass Transition Temperature of Sucrose Solutions and Rice Starch Gel

    JOURNAL OF FOOD SCIENCE, Issue 6 2003
    C.-L. Hsu
    ABSTRACT: The study's objectives were to determine the influence of cooling rate through the primary zone of freezing on Tg in sucrose solutions and rice starch gels. The influence of cooling rate, water content, and annealing on Tg were evaluated. Results indicated that the observed Tg values for sucrose solutions were lower after rapid cooling (70% solids: rapid cooling ,66.7°C; slow cooling ,64.6 °C; 30% solids: rapid cooling ,34.6 °C; slow cooling ,33.3 °C). The Tg values of annealed samples are higher than the Tg of both rapidly and slowly cooled samples (70%: ,44.2 °C; 30%: ,32.7 °C). The Tg of the rice starch gel was ,9.0 °C after rapid cooling and ,7.5 °C after slow cooling. [source]

    Isozyme variation and recent biogeographical history of the long-lived conifer Fitzroya cupressoides

    JOURNAL OF BIOGEOGRAPHY, Issue 2 2000
    A. C. Premoli
    Abstract Aim Palaeoenvironmental records of Pleistocene glaciation and associated vegetation changes in Patagonia have led to the hypothesis that during the last glacial maximum (LGM) tree species survived locally in favourable habitats. If present populations originated from spread from only one refugium, such as an ice-free area of coastal Chile (Single Refugium hypothesis), we would expect that eastern populations would be genetically depauperate and highly similar to western populations. In contrast, if the ice cap was not complete and tree species persisted in forest patches on both slopes of the Andes (Multiple Refugia hypothesis), we would expect a greater degree of genetic divergence between populations either on opposite sides of the Cordillera (Cordillera Effect scenario) or towards its present-day southern distributional limit where the ice sheet reached its maximum coverage (Extent-of-the-Ice scenario). Location We tested this refugia hypothesis using patterns of isozyme variation in populations sampled over the entire modern range of the endemic conifer Fitzroya cupressoides (Mol.) Johnst. (Cupressaceae) in temperate South America. Methods Fresh foliage was collected from twenty-four populations and analysed by horizontal electrophoresis on starch gels. Results Twenty-one putative loci were reliably scored and 52% were polymorphic in at least one population. Populations from the eastern slope of the Andes were genetically more variable than those from the western slope; the former had a greater mean number of alleles per locus, a larger total number of alleles and rare alleles, and higher polymorphism. Genetic identities within western populations were greater than within eastern populations. Discriminant analyses using allelic frequencies of different grouping schedules of populations were non significant when testing for the Single Refugium hypothesis whereas significant results were obtained for the Multiple Refugia hypothesis. Main conclusions Our results indicate that present Fitzroya populations are the result of spreading from at least two, but possibly more, glacial refugia located in Coastal Chile and on the southern flanks of the Andes in Argentina. [source]

    Influence of Cooling Rate on Glass Transition Temperature of Sucrose Solutions and Rice Starch Gel

    JOURNAL OF FOOD SCIENCE, Issue 6 2003
    C.-L. Hsu
    ABSTRACT: The study's objectives were to determine the influence of cooling rate through the primary zone of freezing on Tg in sucrose solutions and rice starch gels. The influence of cooling rate, water content, and annealing on Tg were evaluated. Results indicated that the observed Tg values for sucrose solutions were lower after rapid cooling (70% solids: rapid cooling ,66.7°C; slow cooling ,64.6 °C; 30% solids: rapid cooling ,34.6 °C; slow cooling ,33.3 °C). The Tg values of annealed samples are higher than the Tg of both rapidly and slowly cooled samples (70%: ,44.2 °C; 30%: ,32.7 °C). The Tg of the rice starch gel was ,9.0 °C after rapid cooling and ,7.5 °C after slow cooling. [source]

    Effect of gluten content on recrystallisation kinetics and water mobility in wheat starch gels

    JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 4 2004
    Xin Wang
    Abstract The effect of gluten on starch retrogradation at 5 °C was studied using 1H NMR relaxometry. Gels were made from gluten and starch at 27.8 and 38.5% total solids and with gluten comprising either 10, 15 or 20% of the solids. Changes in the transverse relaxation time constant (T2) were related to water mobility. Mono-exponential analysis of relaxation curves showed that, in general, gluten retarded starch retrogradation. T2 values in gluten gels also decreased during storage, but to a much lesser extent. Distributed exponential analysis showed that two distinct regions of T2 were observed in all samples. During aging, the peak values of both regions shifted to lower values for all gels. Starch gel samples showed the most significant shift, and gluten gels showed the least. The three levels of gluten addition in starch/gluten gels produced similar shifts. For all samples the signal intensity of the less mobile region decreased more dramatically than that of the more mobile region during storage. It was suggested that gluten retards water loss in the granule remnants. Copyright © 2004 Society of Chemical Industry [source]