Effects of the Covalent Cross Link of Anthocyanins and Soy Protein on the Surface Hydrophobicity and Functional Properties of Protein

In order to investigate the effects of covalent interaction of SPI and different concentrations of anthocyanins on the surface hydrophobicity and function of protein under enzymatic and alkaline options. The fluorescence probes were used to characterize the surface hydrophobicity of SPI with and without anthocyanins. The foam expansion,emulsion activity,ζ-potential and particle size measurements were used to study the effects of the covalent interaction on the function of SPI.The results showed that the surface hydrophobicity of the SPI was decreased significantly(p<0.05)after covalently cross-linking anthocyanins,and the concentration of the added anthocyanin was inversely proportional to the surface hydrophobicity of SPI. Especially when the added anthocyanin concentration was 0.05%,compared with SPI,the surface hydrophobicity of anthocyanin-SPI complexes which were formed by enzymatic and alkaline methods(LC3 and AC3)was reduced by 87.71% and 82.71%,respectively. The addition of anthocyanins improved the foaming properties and emulsification properties of SPI. When the concentration of anthocyanins was same,the enzymic method had better effect than the alkaline method. The covalent interaction between SPI and anthocyanins increased the absolute value of ζ-potential of SPI,which made the distribution of droplets in the solution become more uniform,and the stability of the solution become stronger. In particular,the absolute value of the ζ-potential of LC3 was 64.35% and 10.98% higher than that of SPI and AC3,respectively.