BACKGROUNDWheat 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.RESULTSIn 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.CONCLUSIONHIU-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. (c) 2024 Society of Chemical Industry.

Wheat is the most widely produced and consumed food in the world, and it is also one of the eight allergenic foods recognized in the world. Gliadin（Glia） is one of the main allergens that induce wheat allergy. This study aimed to explore the effects of high intensity water bath ultrasound（HIWU） on the structure and antigenicity of Glia. Glia was treated with different ultrasonic power. The results of Western blotting showed that there was a strong immune response before and after ultrasound treatment. Non-competitive enzyme-linked immunosorbent assay（ELISA） showed that HIWU significantly reduced the antigenicity of Glia, and the highest immunosuppression rate was 33.03%±1.72% after 480 W HIWU. Furthermore, SDS-PAGE showed that HIWU did not produce small molecular subunits of Glia but cause aggregation of some protein subunits. HIWU reduced the content of α-helix and β-sheet of Glia to make it disordered. HIWU caused quenching of the fluorescence of Glia, and the content of free sulfhydryl groups in protein increased. Meanwhile, Raman spectroscopy analysis showed that the main conformation of the disulfide bond changed from g-g-g to g-g-t, tyrosine and tryptophan changed from the original embedded state to the exposed state. HIWU altered the secondary and tertiary structures of Glia, resulting in the deletion or destruction of Glia epitopes, thereby effectively inhibiting the antigenicity of Glia. This study will broaden the application of ultrasonic technology in cereal products and provide a theoretical reference for the production of hypoallergenic wheat food.

为解决高添加荞麦挂面的难成型、硬度高、易断条、口感粗糙等问题,对3种不同粒度的荞麦麸皮进行微波、蒸汽和超声处理,然后按照荞麦麸皮:荞麦芯粉:小麦粉=15:45:40(质量比)复配制作高荞麦添加量(60％)面团和荞麦挂面.探究荞麦麸皮粒度和预处理方法对混粉面团的热机械学特性和荞麦挂面品质的影响.结果表明,不同荞麦麸皮粒度及预处理方法对混粉面团流变学特性及荞麦挂面品质有不同的影响.未处理组样品随着粒度减小,麸皮的比表面积增加,面团的稳定时间延长,蛋白质弱化度降低,同时挂面的力学特性和蒸煮损失率呈现先增大后减小的趋势,挂面的最佳蒸煮时间、吸水率、硬度、咀嚼性和拉伸强度明显增加.预处理后,面团的蛋白质弱化度和挂面的蒸煮品质及质构特性得到进一步改善.预处理有效降低了挂面的硬度,其中,超声预处理对挂面的硬度改善效果最佳,而对中等粒度的麸皮进行微波预处理对挂面的力学特性和蒸煮品质改善效果最明显.综上所述,选择合适的粒度进行适当预处理是改善麸皮加工性能的有效途径.

In this study, free radical oxidation was chosen to induce covalent reaction of gliadin (GL) with epigallocatechin gallate. The effects of different ultrasound (US) powers on the enhancement of the covalent reaction were compared with the aim of improving the bioavailability of polyphenols in protein modification. Covalent modification of polyphenols was verified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), high-performance liquid chromatography (HPLC) and the Folin-Ciocalteu assay. The structural changes of the covalent complexes were analyzed by ultraviolet (UV) spectroscopy and circular dichroism (CD) spectroscopy. The results showed that US disrupted weak intra-protein forces, which caused molecular depolymerization. The hydrophilic/hydrophobic amino acid residues of the protein were shifted and the tertiary structure tended to be looser, and this process altered the distribution of groups on the molecule surface and increased the water solubility of the protein. Furthermore, the shift in the spatial structure of GL resulted in the exposure of more enzyme cleavage sites, making its digestion easier. The synergistic effect of US and free radical oxidation increased the loading of antioxidant molecules onto the covalent complexes, resulting in stronger free radical scavenging activity.