title: Retrogradation of Waxy Rice Starch Gel in the Vicinity of the Glass Transition Temperature.
abstract: The retrogradation rate of waxy rice starch gel was investigated during storage at temperatures in the vicinity of the glass transition temperature of a maximally concentrated system (T g '), as it was hypothesized that such temperatures might cause different effects on retrogradation. The T g ' value of fully gelatinized waxy rice starch gel with 50% water content and the enthalpy of melting retrograded amylopectin in the gels were investigated using differential scanning calorimetry. Starch gels were frozen to -30°C and stored at 4, 0, -3, -5, and -8°C for 5 days. The results indicated that the T g ' value of gelatinized starch gel annealed at -7°C for 15 min was -3.5°C. Waxy rice starch gels retrograded significantly when stored at 4°C with a decrease in the enthalpy of melting retrograded starch in samples stored for 5 days at -3, -5, and -8°C, respectively, perhaps due to the more rigid glass matrix and less molecular mobility facilitating starch chain recrystallization at temperatures below T g '. This suggests that retardation of retrogradation of waxy rice starch gel can be achieved at temperature below T g '.
authors.affiliation: Department of Food Science and Technology, Faculty of Agro-Industry, Kasetsart University, Bangkok 10900, Thailand.
authors.forename: Sanguansri
authors.initials: S
authors.lastname: Charoenrein
authors.affiliation: Department of Food Science and Technology, Faculty of Agro-Industry, Kasetsart University, Bangkok 10900, Thailand.
authors.forename: Sunsanee
authors.initials: S
authors.lastname: Udomrati