Improved extraction of protein from soybeans for production of protein concentrates

Factors affecting a method combining enzymatic-chemical and ultrasonic techniques for extraction of protein from heated soybean meal were investigated. The effects of enzyme sonication time, NaOH sonication time, particle size, solvent to meal ratio and enzyme concentration on extraction of protein from soybean meal were investigated and a polynomial regression equation was constructed. Results indicated trypsin concentration, particle size and solvent to meal ratio directly influenced the total protein extraction efficiency whereas time of enzyme sonication and NaOH sonication indirectly affected protein extraction efficiency from heated soybean meal. A multiple regression equation was defined and a R² of 0.9178 was obtained. Soybean protein concentrates obtained by the combined method had a higher protein content and a lower fat content than commercial products.