Multi-scale structure characterization and in vivo digestion of parboiled rice.

ABSTRACT

To investigate the multi-scale structural changes and digestibility of parboiled rice, the side chain distribution, helical structure, short/long-range ordered structure, and lamellar structure were systematically characterized and an in vivo postprandial blood glucose test was applied. The results indicate that parboiling has little effect on the side chain distribution, double helix content and helical structure order of parboiled rice. The crystal type of rice starch changed from type A to A + V or B + V after parboiling and the relative crystallinity decreased from 30.45 % to a minimum of 6.87 %. The in vivo study also indicated that parboiling significantly reduces the glycaemic index of rice to medium level. Our work is the first to focus on the parboiling conditions, multi-scale structural changes and in vivo digestibility of parboiled rice, which might provide guidance for the design of less digestible parboiled rice in the future.