Effect of temperature-cycled retrogradation on slow digestibility of waxy rice starch.

The temperature-cycled retrogradation conditions were optimized for producing slowly digestible starch (SDS) products in this study. The present data showed that the following conditions (temperature cycle, 4/25°C; temperature-cycled time, 14 d; temperature-cycled time interval, 24 h; and ratio of starch to water, 1:2) were available for increasing the SDS yield of the products. The maximum yield reached 54.5%, while the SDS products were prepared under the optimum conditions. The results also indicated that temperature-cycled retrogradation significantly increased the slow digestibility of the SDS products. This was probably attributed to many solid blocks remaining after the hydrolysis of the SDS products by the enzymes for 60 min and 120 min. The solid blocks may comprise of more imperfect crystallites and part of amorphous non-digestible starch. These results suggest that the optimum conditions obtained are suited for preparing SDS products in food and pharmaceutical industries.