In vitro digestion of tofu with different textures using an artificial gastric digestive system

Two kinds of tofu with obvious differences in texture [ GDL and CaSO4 , standing for tofus made with the application of either glucono-delta-lactone (GDL) or calcium sulfate, with measured hardness 23.1 +/- 3.3 g and 105.2 +/- 25.1 g, respectively] were used as to investigate the in vitro progress and extent of tofu digestion, using an independently-developed artificial gastric digestion system (AGDS). The particle size distributions of both CaSO4 and GDL tofu shifted towards smaller particles as the digestion time increased, while the viscosity of the gastric digesta also increased. Tofu proteins were hydrolyzed in the simulated stomach, with GDL tofu showing a higher hydrolysis rate, based on the temporal evolution of SDS-PAGE bands, and had a higher amino acids accumulation than CaSO4 tofu at the end of gastric digestion. In the absence of peptic enzymes, the protein was acidicallyhydrolyzed, but the degree of hydrolysis was much lower than in the presence of enzymes; these findings are in accord with the changes in microstructure observed by scanning electron microscopy. The results indicated that the in vitro extent of tofu digestion is related to its hardness, which is in turn related to its microstructure; they also indicated the potential of our developed in vitro dynamic stomach in studying semi-solid foods.

Automated summary

This study used two types of tofu with different textures to investigate their in vitro digestion. The results showed that the extent of digestion was related to the hardness and microstructure of the tofu. GDL tofu had a higher digestion rate and protein hydrolysis compared to CaSO4 tofu.