Preparation, Physicochemical And Antioxidant Roperties Of Egg Protein Hydrolysates

Egg protein with well balanced amino acid, easy absorption and low prices, has a wideapplication prospect in nutrition and health foods. In addition, Egg white protein (EWP) andegg yolk protein (EYP) have favourable functional properties such as foaming capacity,emulsifying capacity and so on. So egg protein is an important raw materials for food industry.But in the processing process of EWP and EYP, functional properties will have a certaindegree of decline. In order to provide certain theoretical reference on broadening protein’sdevelopment and utilization, this paper has explored that the influence of limited enzymatichydrolysis as a modification method on the functional and antioxidant properties of eggprotein. The main results were showed as follows:1. The physicochemical properties of egg white protein hydrolysates of different DH (5,10,15%) were characterized. The results showed that: preheating treatment (95oC,15min)significantly improved degree of hydrolysis; enzymatic hydrolysis generated a lot of peptides;surface hydrophobicity (Ho) and SH content also decreased. EWPh’ emusifying activities haddramaticly declined, with foaming activities also declined slightly. But protein solubility hadremarkably increased to more than80%. Differences of physicochemical properties weredecided by the decline of molecular weight and Ho.2. The physicochemical properties of two types of egg yolk protein hydrolysates ofdifferent DH (5,8,11,14%) were characterized. The results showed that: enzymatichydrolysis generated a lot of peptides; surface hydrophobicity (Ho) and protein solubilityincreased greatly; emulsifying and foaming properties had greatly improved. No matter whatemulsifying or foaming properties was the best when the DH was8%, which was decided bychanges of protein solubility, molecular weight and Ho jointly.3. Further through four kinds of antioxidant determination methods, antioxidantproperties of EWPh and EYPh were investigated. The results showed that: antioxidantactivities of EWPhs had a certain degree of increase than EWP; and also EYPhs’ antioxidantactivities had increased greatly. The reasons for increasing of antioxidant activities were the change of DH and Ho, decreasing of molecular weight, and improving of solubility.In conclusion, limited enzymatic hydrolysis has obvious effect on improvement of eggyolk protein’s physicochemical and antioxidant properties, and egg white protein’s solubilityand antioxidant properties. But the functional properties of EWP had a certain degree ofdecline by enzymatic hydrolysis. So EWPh and EYPh can be used in food industry asnutritional and functional additives, which will provide new direction and ideas for thedevelopment and utilization of egg protein.