| In order to improve the solubility of rice protein (RP), the solubility modification of RP by enzymatic method in neural condition were investigated. Based on the single factor experiment of five enzymes including neutral protease, alkaline protease, acid protease, bromelain and papain, the combination enzymatic hydrolysis of RP was analyzed. The results showed that the neutral protease had the best efficiency on solubility modification in the single enzyme hydrolysis test. Under the conditions of RP mass concentration 20%, enzyme dosage 1%, enzymolysis temperature 50 ℃ and enzymolysis time 4 h, the instant rice protein (IRP) solubility was up to 79.01%, and the degree of hydrolysis (DH) was 679%. In the combination enzymatic hydrolysis, the effect of neutral protease and papain group was the best. Considering the protein solubility, degree of hydrolysis and functional properties, the ideal solubility modification conditions were obtained as follows: RP mass concentration 20%, using neutral protease and papain, each enzyme dosage 0.5%, enzymolysis temperature 50 ℃and enzymolysis time 4 h. Under these conditions, the IRP had good solubility (6358%), high emulsifying activity (27.60 m2/g) and good emulsion stability (29.61 min), and also had good solubility (5439%-68.34%) in the range of pH 5-8. In addition, the content of free amino acids and peptides increased significantly in IRP, so it had higher nutritional value and was easier to be digested and absorbed. The results indicated that enzymatic hydrolysis with combined proteases was an effective way to increase the solubility of RP, and the solubility and emulsifying properties of IRP could be obviously improved. |
