Influence of structural stability of meat proteins on intragastric digestion kinetics and gastric emptying

Dietary protein regulates gastric emptying, which may further influence postprandial glycemic response and subsequent food intake. However, how different meat protein sources affect gastric emptying and the underlying mechanisms remain unclear. In this study, we compared the effects of meat proteins from chicken, duck, goose, pork, and mutton on gastric emptying rates, dextrin-induced glycemic response, and food intake in rats. Their digestive properties were further analyzed using a static in vitro digestion model to investigate the relationship between protein digestion characteristics and gastric emptying. In vivo results showed that duck and mutton proteins exhibited slower gastric emptying than other proteins, accompanied by attenuated postprandial glycemic response and reduced food intake. In vitro, these proteins exhibited lower gastric digestibility and peptide release, together with greater surface hydrophobicity, higher β-sheet content, and delayed protein degradation and particle size reduction during digestion. These findings suggest that the higher structural stability of meat proteins, as reflected in the retention of β-sheet content and higher surface hydrophobicity, may reduce susceptibility to enzymatic hydrolysis and slow chyme evolution, including particle size reduction and the formation of soluble digestion products, which may contribute to delayed gastric emptying. Our study sheds light on how protein structural properties influence gastric digestion and emptying, providing a basis for designing meat-based foods with specific digestive behaviors and metabolic responses.