Study On The Interaction Between Selenium Acidized Egg Protein And Tea Polyphenols And The Antioxidation Of Its Complex

Egg white protein(EWP) was selenized by dry-heating in the presence of selenite. The selenium content of Se-EWP was0.91%. Incubation EGCG with Se-EWP at30℃and removed at Id. EGCG binding ratio in Se-EWP-EGCG was86.59%. The antioxidant activity of Se-EWP was investigated before and after conjugation of epigalloctechin gallate(EGCG). The antioxidant activities including ABTS+free-radical scavenging capacity,reducing power,surperoxide anion scavenging activity,hydroxyl radical scavenging activity and Fe2+chelating capacity of N-EWP was improved by selenization before and after conjugation of EGCG. The improved antioxidant property of Se-EWP was attributed to the introduced selenium group,more exposed hydrophodic group and more EGCG bond to Se-EWP. Se-EWP-EGCG in the antioxidant system for maximum,may be due to the oxidation resistance of EGCG and selenium played synergistic effect when EGCG and selenium combined with protein.Ovalbumin(OVA) is the major protein component of EWP. It is an important food ingredient with structural functionality predominantly affect the functional properties of EWP. Therefore, monitoring the physicochemical and structural changes of selenized OVA(Se-OVA) by dry-heating in the presence of selenite can further elucidate the relationship between the structural and antioxidant proterties of Se-EWP. In the presnt study,OVA. was selenized by dry-heating in the presence of selenite. The selenium content of Se-OVA was0.85%. Incubation EGCG with Se-OVA at30℃and removed at Id. EGCG binding ratio in Se-OVA-EGCG was88.74%.The antioxidant activity of Se-OVA was investigated before and after conjugation of EGCG.The antioxidant activities of OVA were remarkably improved by selenization before and after conjuction of EGCG. The binding of EGCG to Se-OVA were investigated with spectral methods. Fluorescence quenching of Se-OVA by EGCG were both dynamic and static quenching. The binding contant Ka’s order of magnitudes of EGCG and Se-OVA was104. The number of binding sites n was1. The hydrophobic forces played a predominant role in EGCG and Se-OVA. The effect of EGCG on the conformation of Se-OVA was also analyzed by synchronous fluorescence spectroscopy. EGCG was very close to tyrosine and tryptophan residues in Se-OVA and had impact on both microenvironment. Fourier Transform Infrared Spectroscopy(FT-IR)suggested that the secondary structure change of the Se-OVA had been induced by EGCG. The circular dichroism spectra(CD) showed that the a-helix content of N-OVA decreased by selenization and further decreased by conjugation of EGCG. The transmission electron microscope(TEM) suggested that Se-OVA-EGCG nanocomplex had minimum grain diameter and good dispersion.This study provides a better way for creating antioxidant food, and for the study of other proteins and the interaction mechanism of tea polyphenol laid a certain foundation.