Impact of mechanical and bolus properties on static and dynamic in vitro gastric protein digestion of plant-based meat analogues

Increased food hardness can reduce proteolysis during gastric digestion, but can also lead to smaller bolus particles during mastication, which can enhance proteolysis. The joint influence of mechanical and bolus properties on gastric motility and protein digestion is underexplored. This study investigated the impact of mechanical and bolus properties on static and dynamic in vitro gastric protein digestion of plant-based meat analogues (PBMA). Two commercial PBMA patties (Beyond Meat, THIS) were masticated and subjected to static (INFOGEST) and dynamic gastric-emptying-mimicking digestion (NERDT). THIS patties had higher Young's modulus than Beyond Meat patties and broke down into smaller particles during mastication. During static digestion, THIS patties had lower free amino group concentrations than Beyond Meat patties, probably due to the higher Young's modulus. In contrast, during dynamic digestion, THIS patties showed more free amino groups in emptied liquid and faster gastric emptying than Beyond Meat patties. To further explore the effect of bolus particle size, three model PBMA patties differing only in bolus particle size were digested using static and dynamic models. During dynamic digestion, patties with small bolus particles (<0.18 mm(2)) exhibited more free amino groups than patties with large bolus particles (0.59-0.68 mm(2)). The enhanced digestion was attributed to lower intragastric pH and faster gastric emptying of smaller bolus particles. We conclude that bolus particle size primarily impacts dynamic gastric protein digestion of PBMA patties. Future studies should use dynamic gastricmotility-mimicking models when studying properties sensitive to gastric emptying, and include mastication and bolus characterization before in vitro digestion.