Trypsin and chymotrypsin are necessary for in vitro enzymatic digestion of rice starch

An appropriate in vitro starch digestion model is necessary to comparatively evaluate the digestibility of starch samples and to help predict the in vivo glycemic responses of starchy foods. In the present study, the effect of trypsin and chymotrypsin on in vitro digestion of rice starch was studies for the first time. Inclusion of the trypsin and chymotrypsin in the digestion protocols, to more closely simulate intestinal digestion, increased the hydrolysis percentage of cooked rice and rice starch gels. The hydrolysis kinetics results showed that the digestion rate of cooked rice and starch gels was increased with the addition of trypsin and chymotrypsin in the simulated intestinal fluids. This study showed clearly that the addition of proteases during simulated intestinal digestion is necessary to evaluate accurately the in vitro digestibility of starch or starchy foods.