Interaction mechanism between loach protein and chlorogenic acid and emulsion properties of their complex: a study based on multispectral technology and molecular simulation

This study investigated the binding features, conformational changes, and emulsifying properties of loach protein (LP) with chlorogenic acid (CGA) using multispectral techniques, molecular simulation, and in vitro assays, aiming to clarify aquatic animal protein-polyphenol interactions and promote high-value utilization of LP. LP and CGA spontaneously formed stable non-covalent complexes, with hydrophobic interactions as the main driving force (ΔH = 14.55 kJ/mol, ΔS = 137.40 J/(mol·K), ΔG = -25.51 to -29.89 kJ/mol). CGA induced LP conformational rearrangement, optimized surface charge distribution, and improved dispersibility. The emulsifying and foaming properties of LP were enhanced by CGA in a dose-dependent manner. Specifically, the LP-CGA complex (1:0.1) increased EAI to 268.30 ± 4.73 m²/g and FC to 72.67 ± 3.06% (98.2% increase). ESI peaked at 48.00 ± 2.65 min (1:0.05). After 14 days of storage, the 1:0.1 group maintained a CI of 91.00 ± 3.61%, significantly higher than that of LP (64.67 ± 1.53%). Rheological parameters (n,K) were governed by mechanisms distinct from those of emulsifying properties, reflecting the mechanical strength of the protein network rather than interfacial adsorption behavior. This study elucidates the LP-CGA interaction mechanism, providing theoretical support for LP-based functional food development and stable emulsion system construction.