Studies On Optimized Hydrolysis Condition Of Egg White Protein And The Effect Of Egg White Hydrolyzates On The Liver Antioxidantive Activity In Mice

In this study, Protamex, Neutrase, Alcalase and Flavourzyme were used to hydrolysis egg white and the hydrolysis condition were studied by single factor test and orthogonal design to optimize the technology parameters of temperate, pH, the amount of protease and the concentration of egg white. And the molecular weight distribution and amino acid composition of the hydrolyzates were analysised by HPLC. In addition, egg white hydrolyzates were fed to ICR mice by gastric intubation and the liver antioxidantive activity were determined. The methods and results of the study were as follow:1Egg white protein were hydrolysised by single protease.The optimized hydrolysis conditions of egg white protein by Protamex were55℃, pH7.0the amount of Protamex7%and egg white concentration1:5. Under this condition, the rate of residual protein and degree of hydrolysis were6.82%and7.40%, respectively. The molecular weight of Protamex hydrolyzate were lower than1000Daltons, and the molecular weight of180-300,300-500and500-1000Daltons were33.53%,40.24%and20.67%, respectively. The amount of free amino acid was2.96%.The optimized hydrolysis conditions of egg white protein by Neutrase were55℃, pH6.0the amount of Neutrase5%and egg white concentration1:5. Under this condition, the rate of residual protein and degree of hydrolysis were24.28%and3.71%, respectively. The molecular weight of Neutrase hydrolyzate were lower than1000Daltons, and the molecular weight of180-300,300-500and500-1000Daltons were28.03%,41.84%and23.69%, respectively. The amount of free amino acid was4.32%.The optimized hydrolysis conditions of egg white protein by Alcalase were55℃, pH7.5 the amount of Alcalase5%and egg white concentration1:5. Under this condition, the degree of hydrolysis were18.73%. The molecular weight of Alcalase hydrolyzate were lower than1000Daltons, and the molecular weight of180-300,300-500and500-1000Daltons were31.13%,41.80%and20.71%, respectively. The amount of free amino acid was9.09%.The optimized hydrolysis conditions of egg white protein by Flavourzyme were55℃, pH6.5the amount of Flavourzyme6%and egg white concentration1:5. Under this condition, the rate of residual protein and degree of hydrolysis were27.68%and38.75%, respectively. The molecular weight of Flavourzyme hydrolyzate’s molecular weight of <180and180-300Daltons were17.17%and58.18%, respectively. The amount of free amino acid was44.09%.2Egg white protein were hydrolysised by combined protease.Based on single protease hydrolysis tests, the optimized hydrolysis conditions of egg white protein by Protamex,Neutrase and Flavourzyme were6h, pH6.5, the protease ratio1:1:2, egg white concentration1:5. Under this condition, the degree of hydrolysis were53.24%. The hydrolyzate’s molecular weight lower than300Daltons were68.06%. The amount of free amino acid was44.02%.The optimized hydrolysis conditions of egg white protein with Alcalase and Flavourzyme by steps were egg white concentration1:5, the protease ratio1:2and hydrolysis time was3h,respectively. The hydrolyzate’s molecular weight of<180,180-300and300-500Daltons were11.89%,67.65%and16.05%, respectively. The amount of free amino acid was38.01%.3Antioxidantive activity of egg white hydrolyzates in vivo.Each proteases’hydrolyzates of3h and6h were fed to ICR mice by gastric intubation, the results indicate that compared with control group(NS), egg white protein hydrolyzates all can improve the liver activity of T-SOD and GSH-Px,and inhibit the formation of MDA. Amoung the hydrolyzates, antioxidantive activity of A-3h, P+N+F-6h, A&F hydrolyzates were higher than the non-hydrolysised egg white group.