Endogenous Rice Endosperm Hemicellulose Slows In Vitro Starch Digestibility

Hemicellulose, the primary non-starch polysaccharide originating from cell walls of rice endosperm, greatly influences the digestibility of starch in food matrix. Three rice varieties differing in total dietary fibre content were treated with hemicellulose and in vitro starch digestion with alpha-amylase was conducted. Removing the hemicellulase significantly promoted starch digestion, and the magnitude of the impact was dependent on rice variety. The impact was more pronounced in variety cw high in apparent amylose and total dietary fibre content, while was negligible on the japonica rice Nipponbare. Endogenous hemicellulose slowed in vitro starch digestibility in rice by interacting with amylose and amylopectin, particularly with the long chain amylopectins, inherent existing and during the cooking process. Non-starch polysaccharides, including hemicellulose, can be tailored in rice to modify the digestible carbohydrate content; however, more research is required to fully understand the interactions between non-starch polysaccharides and starch and their influences on grain quality.