Structural modification and functional improvement of lactoferrin through non-covalent and covalent binding to coffee polyphenol

Studies have suggested that milk may enhance or neutralize the bioavailability of coffee polyphenols, possibly due to reversible and irreversible interactions between coffee polyphenols and milk proteins. The effects of non-covalent and covalent binding of lactoferrin (BLF) to caffeic acid (CAA) on protein structure and function were investigated. SDS-PAGE analysis confirmed the covalent interaction between BLF and CAA. Multispectral experiments characterized the BLF-CAA complexes and conjugates, revealing alterations in the tertiary structure of the proteins in the BLF-CAA conjugates. Molecular docking and kinetics results demonstrated that hydrogen bonding, electrostatic interaction, and hydrophobic forces were the primary internal forces between CAA and BLF. When combined with CAA, the covalent conjugates exhibited superior functional properties including solubility, oxidation resistance, thermal stability, emulsification and foamability, bioaccessibility, and antimicrobial properties. This study offers a theoretical foundation and technical benchmark for the preparation of protein-based delivery vectors with synergistic effects. •Non-covalent and covalent conjugation of lactoferrin with caffeic acid were compared.•Conjugates were synthesized using laccase-catalyzed oxidation, free radical grafting, and base treatment.•The binding force of lactoferrin to caffeic acid was predicted using molecular docking and MD.•The covalent conjugates exhibited superior functional properties.