Effect of lycium barbarum polysaccharide on the interaction between caffeic acid and β-lactoglobulin: Multispectral analysis and activity evaluation

Proteins, polysaccharides, and polyphenols are pivotal food components, each endowed with diverse biological functions. Given that the combination between polyphenols and polysaccharides may give rise to synergistic effects, this study explored the impact of lycium barbarum polysaccharide (LBP) on the interaction between caffeic acid (CA) and beta-lactoglobulin (BLG), employing multiple spectroscopic techniques and calorimetry. The investigation revealed the thermodynamic parameters and primary driving forces underlying BLG + CA and (BLG + LBP) + CA interactions. The introduction of LBP diminished the binding affinity of CA for BLG. Notably, CA changed the secondary structure, particle diameter and melting temperature of BLG, with more pronounced effects observed in the presence of LBP. Moreover, the influence of the formation of complexes and nanoparticles on the improved function of CA and BLG was studied, including storage stability, antioxidant activity, and bioaccessibility of CA, as well as the thermal stability and in vitro digestive behavior of BLG. The functional improvement was found to be more pronounced in the presence of LBP and in the nanoparticles. The results revealed that LBP may improve the efficiency of functional products containing BLG and CA.