Design of metastable peanut protein-polyphenol complex particles for tunable flow, interfacial, and gelation properties.

This study investigated the complexation process between peanut protein (PP) and three structurally distinct trace polyphenols-gallic acid (GA), quercetin (QR), and epigallocatechin gallate (EGCG)-followed by spray drying. Spectroscopic analysis indicated that the polyphenols, acting as liquid-phase conformational modulators, guided the peptide chains into compact, α-helix-rich structures through specific noncovalent interactions (hydrophobic embedding for quercetin, and hydrogen bonding for gallic acid and epigallocatechin gallate). Rapid dehydration during the spray-drying process dynamically locks these transient conformations into process-induced metastable particles with unique surface topologies. Functionally, GA forms smooth, low-friction particles whose properties are optimized for rapid interfacial spreading. In contrast, QR and EGCG form rigid, porous aggregates characterized by high interparticle friction; this topological structure provides mechanical interlocking, which is essential for robust Pickering emulsion stabilization, enhanced water-holding capacity, and tunable particle gelation properties. Macroscopic functional tests confirm the existence of a structure-driven fundamental trade-off between rapid interfacial spreading ability and long-term mechanical barrier formation (emulsion stability and overall gelation). This study demonstrates that trace-level polyphenol modification, combined with process-induced kinetic locking, provides a targeted strategy for designing plant protein particle systems with customized flow, interfacial, and gelation behaviors.