Characterization of the protein structure of soymilk fermented by Lactobacillus and evaluation of its potential allergenicity based on the sensitized-cell model

•Fermentation caused change in the advanced structure of proteins.•Fermentation destroyed five human IgE-binding linear epitopes.•Fermented soymilk showed lower antigenicity and potential allergenicity. This study aimed to investigate the effects of fermented soymilk (FSM) with Lactobacillus brevis CICC 23,474 and L. brevis CICC 23,470 on the structural changes and allergenicity of major allergenic proteins in soymilk (SM). Spectroscopy and liquid chromatograph-tandem mass spectrometer (LC-MS/MS) were used to characterize changes in protein spatial structure and epitopes. The antigenicity and potential allergenicity were evaluated by immunoblotting, enzyme-linked immunosorbent assay (ELISA) and KU812 cell degranulation assay. Results suggested that the advanced structure of proteins was destroyed. Antigenicity was also significantly reduced, and five human IgE-binding linear epitopes (i.e., E5-E33, R27-S41, D414-A437, G253-I265 and V449-S471) were destroyed by fermentation. Furthermore, after in vitro simulated gastrointestinal digestion, FSM showed lower IgG/IgE-binding capacity and weaker degranulation ability of KU812 cells. All these findings demonstrated that fermentation with Lactobacillus can destroy the conformational and linear epitopes of proteins and reduce the potential allergenicity of SM.