Influence of annealing temperature on T′g of cooked rice stick noodles

Abstract

T′g, a glass transition temperature under conditions of maximal freeze concentration, is important to the stability of frozen food. The procedures for using differential scanning calorimetry (DSC) to measure T′g have been reported under different experimental conditions. The aims of this study were to investigate the T′g of cooked rice stick noodles, and to determine the effect of the annealing temperature on its T′g value using DSC. Cooked rice stick noodles in aluminum DSC pans were scanned from -60°C to 25°C at 5°C/min. to locate the apparent T′g, which was -5.3°C in the non-annealed state. When subjected to 4 different annealing temperatures of -2, -6, -8 and -10°C for 15 minutes, the T′g of cooked rice stick noodles was -5.3, -4.0, -4.2, and -4.9°C, respectively. The value of T′g was clearly observed in the annealed sample at -6°C. The annealing process allowed time for the maximum formation of ice. This study showed that annealing at a temperature slightly below T′g gave a higher and more accurate value.