Tannic acid/non-covalent interaction-mediated modification of hemp seed proteins: Focused on binding mechanisms, oil-water interface behavior, and rheological properties

In this study, hemp seed protein (HSP) was treated to prepare a hemp seed protein-tannic acid non-covalent complex (Nov-HSP). To obtain an emulsifier with excellent properties at the oil-water interface and to propose a potential mechanism of action. The results showed that the α-helix and β-sheet content of Nov-HSP decreased and the intensity of the UV absorption peak increased, respectively, compared with that of HSP. The positions of the maximum fluorescence emission peaks of the synchronized fluorescence spectra were red-shifted to 301.8 nm and 340.6 nm, respectively. Fluorescence quench analysis revealed that static quench occurred between tannins and HSP, with ΔH of −16.138 kJ/mol and ΔS of −0.1073 kJ/mol. The physicochemical and functional properties of HSP and Nov-HSP were analyzed, and it was found that the volume mean diameter of Nov-HSP was 449.28 nm, the absolute value of zeta potential was 20.52 mV, and the solubility was 33.42% at a tannic acid concentration of 1.0 mg/mL. Focusing on the oil-water interfacial properties of Nov-HSP as an emulsifier, it was found that having non-covalent binding effectively increased the diffusion rate of HSP at the interface, thus enhancing the rheological properties of the emulsion. And the emulsification activity index and emulsion stability index were improved to 71.67 m2/g and 32.01 min. These findings provide new perspectives for the phenolic compound-mediated structural remodeling of HSP, expanding its application in emulsion food production. [Display omitted] •Hemp seed protein-tannic acid non-covalent complexes (Nov-HSP) was prepared.•Non-covalent interactions were dominated by hydrogen bonding and van der Waals force.•Oil-water interfacial behaviors of Nov-HSP were improved.•Non-covalent interactions enhance the ability of proteins to stabilize emulsions.