Impact of tea polyphenols on the regulation of emulsion stability of mayonnaise: a synergistic mechanism based on lipid oxidation inhibition and protein conformational regulation

Mayonnaise is a model high-fat emulsion. The lipid oxidation and protein conformational deterioration in it occur simultaneously and mutually reinforce each other, which ultimately cause structural collapse during storage. In this study, it elucidated a protein–lipid co-regulation mechanism mediated by tea polyphenols (TP), representing a synergistic stabilization strategy rather than a single-path antioxidant intervention. 0.015% (w/w) TP was identified as the optimal concentration at which lipid oxidation inhibition and interfacial protein remodeling were co-activated. At this level, TP formed a compact interfacial adsorption layer, reduced droplet size, and increased the zeta potential to −23.5 mV, thereby strengthening electrostatic repulsion and suppressing early-stage lipid coalescence. Simultaneously, through hydrogen bonding and hydrophobic interactions, TP induced a conformational transition of yolk proteins from α-helix to β-sheet, resulting in a more rigid protein–lipid interfacial film capable of resisting oxidation-driven structural relaxation. The catechol groups of TP scavenged free radicals, increasing the DPPH scavenging rate to 36.63% and markedly lowering peroxide formation, thereby blocking the lipid–protein co-oxidation chain reaction. LF-NMR demonstrated that bound water (T₂₁) increased by 28.82%, reducing water mobility and enhancing freeze–thaw tolerance. Molecular docking further confirmed the preferential binding of TP to yolk lipoproteins (ΔG = −4.63 kcal/mol), explaining the selective stabilization of protein–lipid complexes at the interface. Collectively, these results revealed a dual-mode stabilization mechanism in which TP simultaneously regulated protein conformation and lipid oxidation, providing an innovative molecular design strategy for engineering high-stability emulsified foods.