Effect of Maillard reaction on the allergenicity of crude extract of Mactra quadrangularis

Food allergy incidents resulting from the consumption of Mactra quadrangularis is frequently reported. Investigating the impact of the Maillard reaction on the allergenicity of M. quadrangularis allergens is beneficial for the development of hypoallergenic mollusks aquatic products. This study examined the effects of the reaction products (Mactra-Xyl) on the allergenicity using Maillard reaction between crude extract (Mactra) of M. quadrangularis and xylose. The IgE-binding activity with sera from M. quadrangularis allergic patients and allergenicity potential by a mouse food allergy model of Mactra-Xyl were evaluated. Structural changes of Mactra-Xyl were analyzed by UV spectroscopy and surface hydrophobicity assessment, and the amino acid modification sites of the major allergen tropomyosin were further identified using LC-MS/MS. The sera results showed that the IgE-binding activity of Mactra-Xyl was reduced by 56.66 % ± 15.48 % compared to Mactra. In the BALB/c mouse food allergy model, the levels of specific IgE antibody and CD4⁺IL-4⁺ cells were significantly decreased, whereas the levels of IgG2a antibody and CD4⁺IFN-γ⁺ cells were observably increased in Mactra-Xyl group compared to those observed in Mactra group, thereby alleviating the allergic response. Furthermore, the UV fluorescence intensity and protein surface hydrophobicity of Mactra-Xyl were decreased. LC-MS/MS results revealed that 6 amino acid residues (K₂₁, R₇₇, K₈₆, R₁₄₀, K₁₈₉, N₂₀₂) on 4 IgE epitopes of tropomyosin in Mactra-Xyl were modified, the finding explain the reduced allergenicity of Mactra-Xyl. Therefore, this study provided a theoretical basis for the development of hypoallergenic M. quadrangularis products.