Structural changes in oat milk and an oat milk‒bovine skim milk blend during dynamic in vitro gastric digestion

In recent years, plant-based milk alternatives have become increasingly desirable because of their sustainability and proposed health benefits. There is a need to understand the behavior of plant-based milks during gastric digestion, including protein digestibility, structural changes, and macronutrient accessibility. The aim of this study was to investigate the gastric digestive behaviors of oat milk and an oat milk‒bovine skim milk blend (1:1, v/v), using an in vitro dynamic human gastric simulator. During gastric digestion with pepsin, the oat milk did not show significant changes in structure and physical stability. In contrast, the oat milk‒bovine skim milk blend formed coagulated, curd-like particles, which were induced by the action of pepsin on the milk proteins. The oat oil bodies were incorporated into the curd particles. This difference in gastric digestive behavior significantly altered the rate of gastric emptying. Coagulation of the oat milk‒bovine skim milk blend slowed the gastric emptying of macronutrients, leading to a delay in the release of protein and lipids into the small intestine compared with the oat milk. This study provides insight into the way the food structure modification during gastric digestion impacts nutrient delivery. [Display omitted] •Gastric digestion of oat milk and an oat milk‒skim milk blend (1:1, v/v) was studied.•Oat milk had no significant changes in physical stability during digestion.•Caseins in the milk blend were coagulated by pepsin during gastric digestion.•Partial oat proteins and oil bodies were involved in the casein matrix in the blend.•The milk blend had delayed gastric emptying of both proteins and lipids.