Coordinated molecular reorganization of faba bean protein via dual polyphenol complexation for Pickering emulsion stabilization.

This study investigated the coordinated molecular reorganization of faba bean protein isolate (FBPI) induced by ratio controlled dual polyphenol complexation. Gallic acid (GA) and rutin were selected as model polyphenols with different molecular sizes and interaction characteristics. Their distinct effects on protein structure were further examined in relation to interfacial assembly and Pickering emulsion stability. GA promoted structural reorganization, reducing particle size (207.5 to 194.9 nm) and increasing solubility (89.4 to 96.2%), whereas increasing rutin proportion (≥ 0.8:1.0) enhanced intermolecular associations and structural relaxation. Spectroscopic and thermodynamic analyses revealed that hydrogen bonding and van der Waals interactions governed the formation of protein polyphenol complexes, leading to localized conformational rearrangement and increased accessibility of reactive residues. The optimal rutin:GA ratio of 0.4:1.0 produced complexes with superior interfacial performance, exhibiting the highest adsorbed protein fraction (63.76%), high interfacial concentration (11.50 mg/m2), and the lowest Turbiscan Stability Index (7.6). Interfacial adsorption behavior and microscopic observations confirmed the formation of cohesive protein layers and reduced droplet coalescence. These findings demonstrate that dual polyphenol complexation provides an effective strategy for regulating protein structure and stabilizing particulate interfacial films, offering potential for the development of plant protein-based Pickering emulsions.