Direct observation and evaluation of cooked white and brown rice digestion by gastric digestion simulator provided with peristaltic function

• A gastric digestion simulator (GDS) can evaluate disintegration of cooked rice.
• GDS is capable of simply simulating human gastric peristalsis.
• Disintegration of cooked rice was directly monitored during digestion using GDS.
• Disintegration behavior was affected by the presence of bran layer.

This study evaluates physical digestion for cooked white rice and cooked brown rice using a novel in vitro gastric digestion simulator (GDS). The GDS enabled direct observation of the disintegration of cooked rice in the presence of simulated human gastric peristalsis. The experiments confirmed a steep increase in the disintegration of cooked white rice during the initial 30 min, after which disintegrated contents slowly increased. However, the appearance of liquid phase had little effect on cooked brown rice up to 180 min digestion, likely due to the protective action of the bran layer. Our results indicated that cooked rice particles gradually disintegrated into smaller fractions, depending on the type of cooked rice. The present research uses GDS to provide a better understanding of solid food digestion.