Kinetics of Cooking Presoaked and Unsoaked Dry Legumes: Analysis of Softening Rate of Soybeans and Red Kidney Beans

抄録

The kinetics of hardness changes in soybeans and red kidney beans during cooking were analyzed in presoaked and unsoaked samples. Unsoaked test samples were heated to 10–99.5 °C, and changes in water absorption and hardness were measured. These rates were compared to those of control samples that had been presoaked before cooking. Based on the slope of the line from the first-order plot, softening of dry legumes to reach the optimum edible state occurred through reactions that included “softening due to water absorption” and “softening due to heating”. A two-step reaction was also involved in the “softening due to heating” of soybeans and red kidney beans after reaching hardness of 30 N, which was the lower limit of “softening due to water absorption”. Furthermore, we predicted the precise cooking time with temperature changes by determining the softening rate constants at an arbitrary temperature from the Arrhenius equation.