Retrogradation—Digestibility Relationship of Selected Glutinous and Non-Glutinous Fresh and Stale Cooked Rice

Abstract

This study examined the retrogradation and digestibility relationship of fresh and stale cooked rice of three rice varieties: glutinous (TDK11) and non-glutinous (Doongara and floating rice). The effect of rice variety, degree of milling and retrogradation (staling) of cooked rice on the estimated glycaemic index was determined. Although high-glycaemic index values were obtained for fresh cooked rice of all varieties, staling rice at 4oC for 24 h showed positive effect on floating rice only, yielding intermediate-glycaemic index. The effect of staling on retrogradation rates was corroborated by changes in x-ray diffraction peaks. The thermal and textural properties of rice samples showed higher pasting temperature, final viscosity, and hardness, and lower peak viscosity and adhesiveness for fresh cooked non-glutinous varieties, which were also significantly affected by degree of milling, in terms of hardness, after retrogradation.