Determination and Properties of Starch in Rice

The high resistant starch rice, Gongmi 3, a typical Japonica rice, Nipponbare, and Indica rice 9311 were selected to study the cooking and pH effect on their starches. The results showed that the resistant starch content decreased in the order of no cookingcooking and overnight-holdingcooking. A significant difference existed between no cooking and the other two. The pH effect on the resistant starch content was pH 5.2 pH 6.0 pH 6.9. A significant difference was shown between pH 5.2 and the others, but no difference was found between pH 6.0 and pH 6.9. Among the three rice varieties, the resistant starch content decreased in the order of Gongmi 39311Nipponbare. When the pH of the starch hydrolysis buffer was 6.0, cooking seemed to induce the minimal change in the resistant starch content of the rice. The results were also reproducible with minor differences between the replicates.