Short communicationMixing characterization of liquid contents in human gastric digestion simulator equipped with gastric secretion and emptying

•A continuous-type Gastric Digestion Simulator (c-GDS) has been developed.•c-GDS aims to simulate continuous gastric peristalsis, secretion, and emptying.•c-GDS was characterized by tracer experiment using stained model liquid foods.•Complete mixing flow in c-GDS was observed when model liquid food was water.•Increase of viscosity changed mixing characteristics of c-GDS into plug flow.

This study investigates mixing characteristics of the human stomach using a Gastric Digestion Simulator (GDS). The GDS simulates gastric peristalsis which is considered to have function of mixing gastric contents. The GDS has transparent observation windows for directly observing the contents during the experiment, enabling visualization of the mixing of the contents induced by simulated peristalsis. A continuous-type GDS (c-GDS) equipped with continuous gastric secretion and emptying was used in this study. A tracer experiment using stained model liquid foods (starch syrup solution) shows that model liquid food without starch syrup (Milli-Q) was mixed and emptied according to the theoretical equation of complete mixing flow, whereas model liquid foods with starch syrup concentration exceeding 15 wt% were emptied with almost no mixing according to the theoretical equation of plug flow. Mixing induced by simulated peristalsis would be weak and heterogeneous. There might also be a similar tendency in human stomach.