Proteomic and functional insights into high hydrostatic pressure modification of foxtail millet prolamin: Toward a non-thermal strategy for protein quality tailoring

Heat-treated foxtail millet improves glucose disorders. Prolamin, the main storage protein in foxtail millet, is the key hypoglycemic component, and while heat treatment enhances its function through structural modification, it also reduces nutritional value. High hydrostatic pressure (HHP) offers a non-thermal alternative to modify protein structure while preserving nutrients. Previous HHP studies used isolated prolamin, neglecting whole-grain effects and limiting understanding of structural changes in real food systems. To address this gap and focusing on prolamin, this study applied HHP (200–600 MPa) to whole foxtail millet and used proteomics to analyze changes in storage proteins. There were 41 storage proteins identified in foxtail millet, with 21 showing significant differences. Different pressure levels significantly altered the storage protein profile. In addition, the structural properties of prolamin, the main storage protein in foxtail millet were analysed. The structural properties of prolamin shifted progressively with increasing pressure: water and oil holding capacity, foaming capacity, foaming stability, emulsification activity index and emulsification stability index declined, while particle size increased and zeta potential decreased. Microstructural analysis further revealed protein aggregation and the burial of hydrophobic residues. Finally, correlation analysis identified seven key proteins as core regulators of prolamin’s functional characteristics. Notably, the structure of HHP-treated foxtail millet prolamin resembled that of heat-treated one, suggesting HHP could serve as a viable alternative for modulating protein structure. This work provides a theoretical foundation for applying HHP technology in cereal processing and proposes a strategy for physically tailoring protein quality. • HHP-treated whole millet revealed storage protein changes in real food systems. • Proteomics identified 21 key storage proteins across all groups. • HHP induced the protein aggregation in foxtail millet prolamin. • Seven core storage proteins linked to structural properties of prolamin.