Evaluation of Staling of Cooked Rice by Kinetic Analysis of Texture Changes

Abstract

Five polished rice varieties with different amylose contents were cooked, sealed, and stored at 4°C for 168 h. The slope of first-order plots of hardness and stickiness changed during storage; the change process was divided into two periods: the first and latter halves of the period, each with different rate constants. The rate constant of hardness increase in the first half period was greater for rice with a higher amylose content; conversely, in the latter half period, it was greater for rice with a lower amylose content. The rate constant for stickiness decrease in the latter half was greater than that in the first half, and the higher the amylose content, the larger the rate constant in both periods. By simulating a change in the stickiness-hardness ratio using kinetic parameters with texture changes, the time taken for the quality of cooked rice to deteriorate during storage was predicted.