Study On Antioxidant Activity Of Hydrolysates From Egg White Protein By Protease

Eggs contain abundant nutrients, which play a very important role in human health. Achievements have been acquired dramatically in antitumor, anti-hypertension and immune adjusting. However, systematic study on antioxidant activity of hydrolysates from egg white by protease has not been seen in quantity. Our study, which focus on the antioxidant activity of hydrolysates from egg white powder by protease, prepared and assessed antioxidant activity of high-active antioxidant peptides through ultrafiltration, ion-exchange chromategra-phy and gel filtration chromatography. Therefore, all our work will open a new way for improvement of the added value of egg white protein and further processing and application for eggs.The protease, which prepared strongest superoxide anion radical-scavenging activities hydrolysates from egg white, was chosen from six species. The egg white hydrolysates was obtained by alcalase hydrolysis 5hours, under the condition of pH8.0,50℃,10000U/gprotein With superoxide anion radical relative scavenging activities for index, superoxide anion radical-scavenging activities was the strongest, and the result showed that treated hydrolysates was 4.65%higher than without hydrolysis.Through ultrafiltration, ion-exchange chromatography and gel filtration chromatography, antioxidant peptides were purified from egg white hydrolysates by alcalase (HEW). Antioxidant peptides HEW-2-2-3 of egg white were gotten by the ultrafiltration, DEAE-52 cellulose Ion-exchange and Sephadex G-25 filtration chromatography. The IC50 decreased from 33.41mg/mL to 5.63mg/mL, purification fold nearly 6 and recovery rate of protein 13.42%. With Sephadex G-25 gel filtration chromatography, relative molecular weight of antioxidant peptides was about 273Da. The purity of antioxidant peptides were illustrated by the thin-layer chromatography.Antioxidant peptides HEW-2-2-3 had less free radical-scavenging ability than vitamin C. Among free radical-scavenging capacity of-OH, DPPH-and 02-·, HEW-2-2-3 exhibited stronger ability to scavenge ·OH and DPPH-, and IC50 value was 0.871mg/mL and 0.636mg/mL respectively.02-· scavenging ability of HEW-2-2-3 was weaker, with IC50 5.630mg/mL. Its reductive ability was also very weak. The inhibition of lipid oxidation of antioxidant peptides HEW-2-2-3 was strong, and the effect was mostly same as vitamin E. So antioxidant peptides HEW-2-2-3 of egg white has better antioxidant activity.