Study On Enzymatic Modification Technology Of Rice Dreg Protein By Protease Complex

Rice dreg is the by-products of industrial production of rice syrup. Its protein content is 40-70%(dry basis, more than 70% is gluten), and has good digestibility, hypoallergenic, and high nutritional value. In addition, the composition of the essential amino acids is reasonable and in close proximity to the WHO/FAO recommended ideal mode. In a wide range of p H, rice dreg protein(RDP) has bad solubility leading to its features being far worse than rice protein and limiting its application in food industry.The aim of the study was to explore the functional characteristics and oxidation resistance of rice dreg protein peptide, providing certain theoretical basis for the future application of RDP in food industry. The effect of the enzymatic modification and dynamic high-pressure micro-fluidization(DHPM) treatment on functional characteristics and antioxidant properties of RDP was also studied. The main results of this study were as follows:The three kinds of enzymes(acid protease, neutral protease and alkaline protease) were used to hydrolyze RDP in different proportions respectively. And the formation, influence of functional characteristics and oxidation resistance of protein peptide,were also studied. The results showed that the recovery of the products were more than 30%, the degrees of hydrolysis were between 10% and 20%, and the contents of short peptide were as high as 60% above. The hydrolysates of acid protease and alkaline protease had high content of short peptide and disulfide bonds, and degree of hydrolysis was better. The hydrolysates of neutral protease and alkaline protease had good solubility, hydrophobicity and emulsion stability. However, to the hydrolysates of acid protease and neutral protease, the emulsion ability was the best only. In addition, the protein peptides showed strong properties of antioxidant. In short, the hydrolysates of alkaline protease and neutral protease had good functional properties which had great value of development and utilization.This work was done to investigate the functional characteristics and antioxidant properties of protein peptide, of which was treated by different homogeneous pressure(40MPa, 80 MPa, 120 MPa, 160MPa) of DHPM and different kinds of enzymes(alkaline protease, neutral protease, the mixture of alkaline protease and neutral protease which was mixed by 1:1). The results showed that the solubility of hydrolysates was improved with the increase of homogeneous pressure by DHPM. The surface hydrophobicity enhanced gradually, and reached the maximum in 120 MPa. However, homogeneous pressure played a negative role to protein peptide in emulsifying property, and little influence on the stability of emulsion. Through the test of fourier transform infrared spectrometry(FTIR), the main functional groups of peptide didn’t have big change but the degree of ionization and the charge distribution on the surface of protein molecules were increased. At the same time, the antioxidant capacity of protein peptides showed strong antioxidant capacities with the rising of concentration.