Unlocking the antioxidant potential of wheat gluten: structural transitions and peptide release driven by ultrasonication-assisted pH shifting.
Abstract
This study establishes that combined ultrasonication and pH-shifting treatment effectively valorizes wheat gluten, leading to improved enzymatic hydrolysis and antioxidant peptide release. The treatment triggers a molecular restructuring, characterized by weakened hydrophobic interactions and intensified covalent bonds, and shifting from β-sheets to β-turns. These structural modifications lead to significant functional improvements: solubility increased from 3.9% to 11.2%, while dispersion stability was enhanced. Process optimization revealed treatment at pH 9 maximized enzymatic hydrolysis efficiency (protein recovery increased from 83.82% to 88.49%) and DPPH radical scavenging capacity (89.32% to 92.36%), whereas pH 12 combined with 200 W ultrasonication yielded superior ABTS radical scavenging activity (54.73%). Mechanistically, structural unfolding exposed hydrophobic and aromatic amino acids (e.g., Trp), facilitating the release of bioactive peptides. Notably, the identified peptide LWAWW exhibited strong Keap1 binding affinity (-9.5 kcal/mol). This work provides an efficient, sustainable strategy for transforming wheat gluten into high-value, functional food ingredients.