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Cereal Chem. 71:202-207   |  VIEW ARTICLE

Phase Transitions of Rice Starch and Flour Gels.

R.-M. Huang, W.-H. Chang, Y.-H. Chang, and C.-Y. Lii. Copyright 1994 by the American Association of Cereal Chemists, Inc. 

The phase transition temperatures (glass transition temperature [Tg] and melting temperature [Tm]) of 10- 50% (w/w) starch and flour gels from waxy, japonica, and indica varieties of rice were studied by differential scanning calorimetry. Effects of additives and storage conditions were also investigated. The Tg of all samples we examined ranged from -10 to -5 C. The Tm and the enthalpy ((Delta)H) of ice melting increased with increased moisture contents of the samples. When the concentration of starch used was higher than 40%, two endotherms of ice melting and one exotherm between Tg and Tm were observed. The Tg of starch and flour gels under the same concentration were similar, and there were no significant differences among the varieties. The addition of sucrose or sodium chloride decreased the Tg. Tg of 40% rice starch and flour gels decreased to -12 approximately -15 C and to -13 approximately -19 C with the addition of 20% sucrose and 5% sodium chloride, respectively. Tg of rice starch gels increased progressively during the storage. The extent of the increase was affected by the storage temperature (5 greater than -5 greater than -18 C).

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