Comparison of binding interaction between β-lactoglobulin and three common polyphenols using multi-spectroscopy and modeling methods

Tea, coffee and fruit in dairy products are rich in polyphenols. The interaction mechanism between β-lactoglobulin (β-LG) and chlorogenic acid (CGA), ferulic acid (FA) and epigallocatechin-3-gallate (EGCG) was investigated. Fluorescence experiments proved that polyphenols quenched β-LG fluorescence strongly in static mode and EGCG had stronger binding affinity toward β-LG than CGA and FA. The main interaction force of EGCG binding with β-LG was different from CGA and FA. Furthermore, circular dichroism and fourier transform infrared data indicated that polyphenols changed β-LG secondary structure inducing a-helix to β-structures transition. The surface hydrophobicity of β-LG was also changed slightly by them according to surface hydrophobicity and particle size experiments. These results showed that the interaction mechanism of β-LG with phenolic acid esters was different from it with phenolic acids. Besides, polyphenols had impact on the structure and functionality of β-LG, which would be valuable in dairy processing industry.