Modeling the softening of carbohydrate-based foods during simulated gastric digestion

Food breakdown during gastric digestion is important for controlling processes such as gastric emptying. Six foods (brown rice, couscous, orzo, pretzel, quinoa, and white rice) underwent in vitro digestion by incubation in simulated oral and gastric fluids for up to 240 min (100 rpm, 37 °C). Texture analyses were completed by single compression (50% strain) or bulk compression (33 or 67% strain); softening kinetics were fit to the Weibull model. Texture was significantly influenced by food, digestion time, and their interaction (p < 0.0001). Pretzels had the highest initial hardness (59 N) and the fastest softening half time (4 min); quinoa had the lowest initial hardness (1.7 N) and the slowest softening half time (354 min). Softening half times was characterized as: fast (pretzel), intermediate (brown rice, orzo, white rice), or slow (couscous and quinoa). It is recommended that future studies use single compression tests on foods digested for 120-240 min.