Research on solubility improvement of acid extracted rice protein by enzymatic hydrolysis

Enzymolysis treated by neutral protease can increase the solubility of acid extracted rice protein in water.The reaction condition of enzymatic hydrolysis is milder than that of acid or alkaline hydrolysis,and it can keep the nutrient value of protein.The protein solubility in water at pH 4.0 and 5.0 was studied,under various conditions such as the enzymolysis time,enzymolysis temperature,pH,solid-to-liquid ratio and the usage of enzyme.Then these factors were optimized by orthogonal level grading analysis,and the best enzymolysis condition of protein solubility was got as follows: usage of enzyme 40 U per 100 g rice protein,enzymolysis reacted at 50 ℃,pH 7.0 for 2 h and the solid-to-liquid ratio 1∶5.The condition of protein enzymolysis was optimized and rice protein was powdered by spray drying.Its solubility was 65.5%.The product could substitute the soybean protein and would be widely used as high protein food and nutrient supplement in various kinds of food processing.