Effect of warm water soaking for raw rough rice on in vitro starch digestibility of cooked rice

The present study investigated the influence of mild heat treatment on harvested raw rough rice (Oryza sativa L. cv. Toyomeki) by warm water soaking at 65 °C with respect to the physicochemical properties and starch digestibility of cooked rice. Changes in color, texture, starch attributes and simulated in vitro digestibility were examined. The results indicated that the b* value increased with a soaking duration, but the treated rice showed little change in the whiteness index value compared to untreated rice. No significant differences were also observed in the resistant starch content and kinetic constant. A positive correlation was found between firmness and adhesiveness of the cooked (P < 0.01). However, the treated rice showed a lower equilibrium level of starch hydrolysis than untreated rice. The application of mild heat soaking treatment for raw rough rice could be considered an effective technique to control the potential health-related properties of cooked rice.