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

Area of Science:

• Food Science
• Biochemistry
• Dairy Technology

Background:

• Dairy products contain polyphenols from sources like tea, coffee, and fruits.
• Beta-lactoglobulin (β-LG) is a major whey protein in milk.

Purpose of the Study:

• To investigate the interaction mechanisms between β-LG and specific polyphenols: chlorogenic acid (CGA), ferulic acid (FA), and epigallocatechin-3-gallate (EGCG).
• To understand how these polyphenol-protein interactions affect the structure and functionality of β-LG.

Main Methods:

• Fluorescence spectroscopy to assess binding affinity and quenching mechanisms.
• Circular dichroism (CD) and Fourier transform infrared (FTIR) spectroscopy to analyze changes in protein secondary structure.
• Surface hydrophobicity and particle size analysis to evaluate alterations in protein surface properties.

Main Results:

• Polyphenols, particularly EGCG, strongly quenched β-LG fluorescence, indicating significant binding.
• EGCG exhibited a higher binding affinity to β-LG compared to CGA and FA.
• Polyphenol binding induced a transition in β-LG secondary structure from alpha-helix to beta-structures.
• Surface hydrophobicity of β-LG was slightly altered by polyphenol interactions.
• Distinct interaction mechanisms were observed between β-LG and phenolic acid esters versus phenolic acids.

Conclusions:

• Polyphenols significantly impact the structural conformation and surface properties of β-LG.
• The findings highlight differences in interaction mechanisms based on polyphenol chemical structure (e.g., phenolic acids vs. esters).
• Understanding these interactions is crucial for optimizing polyphenol stability and functionality in dairy processing applications.