Insight into the effect of lactic acid fermentation on soy protein immunoreactivity: emphasizing the difference in epitope destruction of varied fermentation terminal pH levels during gastrointestinal digestion

Abstract

This study delves into the immunoreactivity of lactic acid bacterium (LAB)-fermented soy protein isolates (FSPIs), with various structural features, during gastrointestinal digestion and absorption. Additionally, the structural breakdown and epitope degradation of major allergens were investigated for their gastrointestinal behavior. Allergenicity and IgE-binding capacity assays revealed that at the initial and middle stages of digestion, FSPI-5.0/4.0 exhibited greater ability to reduce immunoreactivity than FSPI-7.0/6.0 and reduced immunoreactivity by 1.9%–36.6%. Caco-2 model transport studies further suggested that FSPI-5.0/4.0 T-5 and T-30 samples decreased immunoreactivity by inducing Th1-dominant differentiation. Peptidomics and bioinformatics analyses corroborated these findings, revealing that FSPI-5.0/4.0 promoted the epitope destruction of basic 7S globulin, β-conglycinin, P34, and glycinin and was dominated by secondary structures consisting of α-helices and β-sheets. Therefore, structural control through LAB fermentation represents a promising strategy for regulating the degradation of allergen epitopes.