Abstract:The objective of this study was to quantitatively investigate the effects of changes in gastrointestinal physiological conditions caused by aging on gastric emptying and dynamic digestion characteristics of cooked rice for the elderly. Based on the differences in the gastrointestinal physiological conditions between the elderly and young adults, the gastric physiological digestive environment of the elderly was constructed by the dynamic in vitro human gastric digestive system. Then, the effects of cold storage time (6, 24, 48 h) at 4 ℃ on the gastric emptying and starch hydrolysis kinetics of the cooked rice during dynamic in vitro gastric digestion for the elderly were investigated. The changes of water content, texture and microstructure of the refrigerated rice were analyzed by static immersion tests. The results showed that with the increase of cold storage duration, a denser microstructure of cooked rice was shown during static soaking, leading to a significantly decreased water holding capacity of rice and the significantly increased indentation hardness of rice. Accordingly, the gastric emptying half-time (t 1/2 ) significantly increased from 303.3 min to 630.6 min, and the starch digestibility decreased from 15.4% to 7.4% after 48 h cold storage. The results showed that the gastric emptying rate of the cooked rice after long-term cold storage would potentially be delayed and the rate of starch hydrolysis might be significantly reduced in the digestive environment of the elderly. This study has provided theoretical guidance for understanding of rice digestion for the elderly and the selection and optimization of food processing/storage methods, contributing to the development of starch-based staple food more suitable for the elderly.
