Effect of hydrogel particle mechanical properties on their disintegration behavior using a gastric digestion simulator

Abstract The interest in designing novel foods whose digestibility can be controlled based on life stage and health conditions continues to grow. Physical digestion is important for solid foods as their breakdown and resulting size reduction can promote enzymatic reactions. Our human gastric digestion simulator (GDS) enables the simulation and direct observation of food particle disintegration induced by simulated antrum contraction waves. The objectives of this study were to verify the disintegration performance of the GDS compared with previously reported in vivo data and evaluate the effects of the mechanical properties of hydrogel particles on their in vitro gastric disintegration behavior. Agar beads with four fracture forces were prepared and mixed with meal containing locust bean gum to adjust viscosity same as their in vivo data. The half residence time of intact beads was longer for hard agar beads than for soft agar beads, and a similar disintegration trend to in vivo data was obtained. Moreover, as solid food models, 5-mm hydrogel cubes with different fracture stresses and fracture strains were prepared by varying the agar and native type gellan gum concentrations. The hydrogel cubes disintegrated because of fracture and abrasion during in vitro gastric digestion in the presence of simulated antrum contraction waves. The degree of hydrogel cube disintegration was affected by their fracture strain rather than their fracture stress and was suppressed when their fracture strain was greater than 30%. Our findings may provide a better understanding of the gastric digestion behavior of solid foods with different mechanical properties.