Selective precipitation-induced conformational modulation of pea proteins enhances adsorption at the oil–water interface

This study demonstrates a selective, pH-driven precipitation approach to isolate pea protein fractions with distinct interfacial adsorption behaviour and enhanced emulsifying performance. Compared with the isoelectric precipitates obtained at pH 5 (PP5), the fraction isolated at pH 4 (PP4) exhibited markedly improved emulsifying efficiency and stability. Physicochemical characterisation revealed that this enhancement is associated with altered molecular interactions, whereby PP4 exhibits reduced protein-protein interactions and a more favorable thermodynamic solvent environment (i.e., solvent quality), effectively suppressing aggregation. By modulating ionic strength to decouple surface charge from hydrophobicity, we identified that the better emulsification of PP4 is primarily driven by its exposed hydrophobic patches rather than electrostatic repulsion alone. Interfacial kinetic analysis combined with geometric packing considerations revealed a two-stage adsorption mechanism, involving rapid diffusion and initial monolayer formation, followed by interfacial rearrangement into a complex, highly loaded heterogeneous network exceeding theoretical hexamer monolayer coverage. Upon heating, emulsions stabilised with PP4 formed gels with a soft texture resembling that of egg gels, outperforming those prepared with PP5. Overall, this work presents a mechanistic approach for engineering plant protein interfaces by modulating molecular interactions and regulating adsorption reconfiguration.