Study On The Extraction And Modification Of Rice Protein

In this paper, the extraction process, functional property and modification of japonica rice protein are studied. The aim is to improve the functional property and exploit a rice protein product. It provides gist and technological bases for the further development and utilization of rice resources. The main results are as follows:The optimum extraction conditions of Alkali-protease is as follows: temperature 58℃, pH 8.5, the material-liquid ratio 9:1, enzyme/substrate1000 U/g,the time 4h. The ratio of extraction can reach 70.5%, and the purity can reach 66.53%.The rice protein extraction by the physical-Enzymatic, dual enzyme and the two-step method of alkaline–enzyme are studied. The results show that the three methods can increase the extraction rate of rice protein, and the effect of the two-step method of alkaline-enzyme is significant. The optimum extraction conditions of the two-step method of alkaline-enzyme: alkaline extraction, pH11.0, temperature50℃, time 3 h and the material-liquid ratio:8:1; alkali-proteased extraction, temperature: 55℃, pH:8.5, the material-liquid ratio:9:1, enzyme/substrate:750 U/g, the time 2 h. The ratio of extraction can reach 90.21%, and the purity can reach 83.34%.The effect of pH on solubility, emulsifying properties, and foaming properties of two rice protein( alkaline and protease ) are studied.The modification of rice protein by alkaline Nanning alkaline protease is researched. The best modified conditions: enzyme in5000 u/g, pH9.5, temperature 55℃and hydrolysis time 2 h and rice protein has the dissolution rate of 85.45%.The rice protein functional properties of different hydrolysi conditions, are compared. The results show that 8% of the DH for the rice protein has good solubility, emulsifying and foaming properties. With the DH increase, rice protein hydrolysis emulsification and excessive foaming characteristics were decreased in different degrees. And the amino acid compositions have no significant changes. The experimental results show that the relationship between solubility and hydrolysis in different hydrolysis conditions prove when joined with the more protease or reaction time,the distribution in the soluble protein hydrolysis has a higher proportion of the protease.And on the basis of modification by protease, the effect of TGase on rice protein of 16% DH was studied.