Hydrolysis of soybean protein isolate by papain and neutral protease.

The feasibility of hydrolysis of heat-treated soybean protein isolate (SPI) by papain and neutral protease was studied. Single factor experiment showed that the optimum conditions for papain catalyzed hydrolysis of SPI were as follows: papain dosage 30 μg/g, mass concentration of substrate 3.0%, hydrolysis temperature 55 ℃ and pH 7.0. For neutral protease catalyzed hydrolysis of SPI, the best conditions were neutral protease dosage 40μg/g, mass concentration of substrate 5.0%, hydrolysis temperature 55 ℃, and pH 7.0. Under the above-mentioned two kinds of conditions the hydrolysis degree of protein reached 3.69% and 9.80%, respectively. It was also found that hydrolysis by mixed enzymes was more efficient than that by single enzyme.