Development of a Gastric Simulation Model (GSM) incorporating gastric geometry and peristalsis for food digestion study.

There has been growing interest in developing in vitro gastrointestinal models as alternatives to in vivo tests, which is challenging ethically and financially. An in vitro Gastric Simulation Model (GSM) was developed to reproduce the geometry and motility of human stomach. The peristalsis was generated by a series of syringes squeezing a latex chamber pneumatically. In particular, the distribution, amplitude and frequency of contractions demonstrated similar patterns as in human gastric conditions. The breakdown kinetics and size distribution of sausage particles during the digestion were investigated in GSM to demonstrate the effect of the contraction force. Furthermore, the gastric emptying of water-soluble nutrient (methylene blue) and nondigestible solids (amberlite beads) was investigated. The results indicated that the viscosity of the gastric digesta significantly affected the local flow and emptying behavior of nutrients and solids. This study illustrated the capability of GSM to recreate the transient physiological conditions and dynamic flow of gastric contents due to its specificity of geometry and contraction patterns. The new model can be used to investigate the influence of food matrix and physiological conditions, including gastric secretion and contraction forces on transit and digestion of foods in the stomach.