Characteristics and purification of soybean milk curdling enzyme-producing yeast saccharomyces bayanus SCY003

Abstract

Soybeans and the processed food, soybean milk, have important health functions. A cheese-like food produced from soybean milk resembles casein protein in its mouthfeel and physical properties. The intracellular soybean milk curdling enzyme-producing Saccharomyces bayanus SCY003 strain was screened. The curdling enzyme is an intracellular protease, a 45 kDa monomer protein that degrades soy protein subunits, produced by this strain. The optimum temperature and pH of enzyme activity are 50°C and pH 7.5, respectively. The protease degrades β-conglycinin and parts of glycinin in soy protein to α', α and β subunits. The rheological characteristics of the resultant curd were assessed, and revealed that elasticity differed from curd produced by glucono δ-lactone, which is used in tofu production. A new soy protein food having health-supporting functions will be developed using this protease.