Abstract: In order to find an effective method to reduce the immunogenicity of egg white protein, the immunogenicity of egg white protein was determined by enzyme-linked immunosorbent assay (ELISA) and its structural characterization was carried out by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Fourier transform infrared (FTIR) spectroscopy, fluorescence spectroscopy and ultraviolet (UV) spectroscopy after being treated by microwave, enzymatic hydrolysis or microwave-assisted enzymatic hydrolysis. The results showed that microwave treatment at 700 W for 20 s and alkaline protease hydrolysis decreased the immunogenicity of egg white protein by 50.81% and 55.83%, respectively. A more pronounced effect was observed with microwave-assisted enzymatic hydrolysis, decreasing the immunogenicity of egg white protein by up to 67.48%. The SDS-PAGE band pattern changed after each treatment. Fluorescence spectroscopic results demonstrated that the three treatments could alter the microenvironment of amino acid residues. FTIR spectra indicated the transformation of the secondary structure of egg white protein to a disordered conformation and changes in both secondary and tertiary structures. In addition, the surface hydrophobicity increased after the treatments. These results suggested that the reduction in the immunogenicity of egg white protein may be related to its structural change. Microwave-assisted enzymatic hydrolysis is more effective than either alone in reducing the immunogenicity of egg white protein.

Key words: egg white protein; microwave-assisted enzymatic hydrolysis; immunogenicity; structure