Abstract: This paper is focused on the effect of interaction with anthocyanin on the structure and function of denatured soybean protein. Fluorescence spectroscopy was used to study the conformational changes of the complexes. The relationship between structural change and functional properties was analyzed through determination of solubility, emulsifying ability, emulsifying stability, particle size analysis and Zeta potential analysis. The results showed that the absolute value of Zeta potential as well as emulsifying activity and emulsion stability of denatured soybean protein increased significantly after complexation with anthocyanin at pH 7.4, whereas its solubility decreased. The fluorescence spectra showed that the fluorescence quenching of heat-treated soybean protein by anthocyanin was a static quenching process with the formation of binding sites close to 1. The three dimensional fluorescence spectra indicated that complexation with anthocyanin extended the protein polypeptide backbone and changed the protein structures.

Key words: soybean protein isolate, anthocyanin, structural property, functional property