Egg White Protein Dry Heating Selenium Acidification And Its Features

Selenizated egg white protein (Se-EWP) was prepared by dry-heating in the presence of selenite, and its physicochemical properties and functional properties were investigated.Firstly, EWP was selenizated by dry-heating in the presence of selenite. The effects of pH, heating temperature and heating time on selenization of EWP were studied. The results showed that the more aggregation and lower solubility were caused at higher temperature, lower pH and longer heating time. Thus the most appropiate condition of selenization was:pH3.0,60℃for3days (d), and the organic selenium content of Se-EWP was0.93%;Secondly, the physicochemical properties of Se-EWP were investigated. The selenite group was acid-stable and base-labile, suggesting that selenite group was bound to hydroxyl group of an amino acid, and formed a—O-SeHO2linkage.The77Se-NMR spectral data also suggested that the selenite bond (—SeHO2) was bound to EWP, which was consistent with the stability of selenite group. Native-PAGE showed the electorphoretic mobility of EWP was increased with the increase of the selenization level; SDS-PAGE showed heat-induced polymerization of EWP was promoted by dry-heating in the presence of selenite.Thirdly, the functional properties of Se-EWP were investigated. Except for solubility of Se-EWP was slightly reduced, the other functional properties, including the heat stability, emulsifying property, foaming property, and oil absorption were improved remarkably by selenization. Fourthermore the solubilization of calcium phosphate of EWP was given by selsnization.Selenization egg white peptide was prepared by incubation EWP with pepsin and the In vitro antioxidant capacities were investigated. The scavenging activity of selenization egg white peptide against2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl, and anti-lipid peroxidation ability was higher than egg white peptide. The results suggested selenization egg white peptide had better antioxidant activity than egg white peptide. The antioxidant activity of egg white peptide was enhanced by selenization.In summary, in the dry-heating condition, selenium can be successfully connected on the egg white protein molecule in the presence of selenite. The form of selenium in Se-EWP was—O-SeHO2. The functional properties of Se-EWP were improved by selsnization. The elenization egg white peptide had better antioxidant activity. These results suggested that dry-heating selenization was a novel method for improvement the functional properties of food protein. This method also provides a new method for preparing organic selenium.