Subunit-dependent Interfacial Assembly of Wheat Gliadin Subunits by Lycium Barbarum Polysaccharide Underlies Foam Stabilization

Protein foams are governed by interfacial adsorption kinetics and film stability, yet the subunit-specific regulation of wheat gliadins by polysaccharides remains unclear. Here, the differential responses of α- and ω-gliadin to Lycium barbarum polysaccharide (LBP) were systematically elucidated by integrating interfacial tension kinetics, foaming performance, multiscale structure, and atomistic molecular dynamics (MD) simulations. Under the matched solvent conditions, α-gliadin exhibited higher foaming capacity and stability than ω-gliadin. LBP significantly enhanced the foam stability of both systems but through distinct mechanisms: α-gliadin exhibited β-sheet enrichment and altered aggregation behavior, accompanied by prolonged foam half-life and reduced drainage, whereas ω-gliadin showed increased conformational flexibility, surface charge, and dispersion stability, accompanied by faster apparent interfacial adsorption, prolonged foam half-life, and suppressed drainage. MD simulations further suggested that LBP was associated with a more compact and less solvent-exposed α-gliadin conformation, whereas ω-gliadin retained greater conformational variability and more transient protein–polysaccharide contacts within the sampled trajectories. Together, these results indicate subunit-dependent structural and interfacial responses of gliadin to LBP and provide molecular-level insights into the differential regulation of α- and ω-gliadin in plant protein foams.