Study Of Function Characteristics Of Hydrolysates From Egg White Protein

Eggs have rich nutritive value.It is a kind of the important source of the nutrition.After the egg white is hydrolyzed by appropriate protease,it will not only improve its function characteristics and reduce the allergen,but also produce some small peptides with special biology active.This enhances the value of the egg white,and open a new way for the deep processing of egg white.Egg white protein is the ideal food proteins.In this paper,the egg white powder was used as raw material,the conditions of hydrolyzing egg white powder,and physicochemical property and bioactivity after hydrolysis were studied.In this study,four kinds of proteases with different sources and work condition were uesd.Through the comparison of hydrolytic degrees curve of the egg white powder hydrolyzed by four proteases,the alcalase with the highest hydrolyzing degree was selected.The results obtained from the orthogonal experiment showed that the optimum for preparing egg white powder was 1%egg white protein,enzyme dosage 11000U/g protein,pH 10.5,the temperature 62?,hydrolysis time 3 h.The degree of hydrolysis was 82.40%.the proportion of hydrolysate of different molecular weight:<1KD 11.3%,1-3KD 18.51%,3-5KD 42.26%,5-10KD 12.58%,>10KD 15.35%.Study shows that:after the hrdrolysis of egg white power,the solubility was increased,the foaming and foam stability were slightly reduced,the emulsifying property was enhanced,the emulsion stability and turbidity were decreased.After the separation of egg white protein hydrolyzate by ultrafiltration,the solubility was decreased with MWCO,the foaming and foam stability were increased with MWCO,the emulsifying capacity and emulsion stability were increased gradually according to MWCO,the turbidity was increased with MWCO.Compared with unfractionated hydrolyzate,the solubility,foaming and foam stability were reduced,the emulsifying property was not significantly enhanced,the emulsion stability and turbidity were increased.The hydrolysate of egg white protein has oxidation resistance.The reduction capability of hydrolyzate was 1/15 of the vitamin C in the concentration of 10mg/mL;the IC50 of hydroxyl radicals,superoxide radicals and DPPH radical scavenging effect were 0.207mg/mL,17.398mg/mL,0.956mg/mL respectively.The hydrolyzate can inhibit thrombin activity in some degrees,the MWCO of active polypeptide was<1KD.The hydrolysates did not inhibit the activity of alpha-glucosidase,and no inhibitory effect on E.coli and Bacillus subtilis.The anti-oxidative capacity of hydrolysates related to the restriction sites,the amino acid composition of egg white protein,the conditions of hydrolysis.