Ultrasound‐enhanced covalent reaction of gliadin: the inhibition of antigenicity and its potential mechanisms

Abstract BACKGROUND Wheat proteins can be divided into water/salt‐soluble protein (albumin/globulin) and water/salt‐insoluble protein (gliadins and glutenins (Glu)) according to solubility. Gliadins (Glia) are one of the major allergens in wheat. The inhibition of Glia antigenicity by conventional processing techniques was not satisfactory. RESULTS In this study, free radical oxidation was used to induce covalent reactions. The effects of covalent reactions by high‐intensity ultrasound (HIU) of different powers was compared. The enhancement of covalent grafting effectiveness between gliadin and (−)‐epigallo‐catechin 3‐gallate (EGCG) was confirmed by sodium dodecyl sulfate–polyacrylamide gel electrophoresis, matrix‐assisted laser desorption/ionization–time‐of‐flight–mass spectrometry and Folin–Ciocalteu tests. HIU caused protein deconvolution and disrupted the intrastrand disulfide bonds that maintain the tertiary structure, causing a shift in the side chain structure, as proved by Fourier, fluorescence and Raman spectroscopic analysis. Comparatively, the antigenic response of the conjugates formed in the sonication environment was significantly weaker, while these conjugates were more readily hydrolyzed and less antigenic during simulated gastrointestinal fluid digestion. CONCLUSION HIU‐enhanced free radical oxidation caused further transformation of the spatial structure of Glia, which hid or destroyed the antigenic epitope, effectively inhibiting protein antigenicity. This study widened the application of polyphenol modification in the inhibition of wheat allergens. © 2024 Society of Chemical Industry.