In vitro gastric digestion of cooked white and brown rice using a dynamic rat stomach model

The changes in physical, rheological and enzyme-digestive behaviours of cooked white and brown rice, with similar amylose content, were investigated using a dynamic in vitro rat stomach (DIVRS) model and a static soaking method. The brown rice had a higher resistance on disintegration and lower gastric emptying rate with 53% of the brown rice particles retained in the stomach at the end compared to 32% for the white rice. Furthermore, the release rate of maltose from the starch hydrolysis was higher in the white rice throughout the digestion suggesting the lower glycemic potency of the brown rice. These differences could be contributed from the rigid bran layer in the brown rice which would inhibit the moisture absorption into rice kernels, limit textural degradation, and generate higher gastric digesta viscosity leading to lower mixing and mass transfer efficiency. This study suggests that the structural difference could affect physiochemical properties during gastric digestion.