Abstract
The effect of soaking and freezing before cooking on the softening rate of Azuki beans was studied. Azuki beans were soaked in deionized water at 20°C for 22 h and then frozen at-40°C for 24 h. The softening by cooking the samples was approximated by first-order reactionh kinetics, and the softening rate constant was obtained from the hardness values measured by a texturometer. The rate constants at 99.5°C with no treatment, soaking-only treatment, and freezing after soaking treatment were 0.070, 0.089 and 0.110 (min-1) respectively. Optimum cooking times at 99.5°C, which were calculated by using the softening rate constant and optimum softening ratio with no treatment, soaking-only treatment, and freezing after soaking treatment, were 71.7, 32.3 and 24.2 min. We conclude that the freezing after soaking treatment before cooking enhanced the softening rate of Azuki beans and that this treatment could shorten the cooking time required for Azuki beans by up to 34% when compared with the time for the nontreated samples.
