Gut microbiota plays an important role in food allergy. The immunoglobulin G (IgG)/ immunoglobulin E (IgE) binding capacity and human gut microbiota changes of digestion products derived from glycated ovalbumin (OVA) were investigated. Gastrointestinal digestion effectively destroyed the primary structure of glycated OVA, resulting in a significantly higher digestibility than gastric digestion, and more abundant peptides below 3 kDa. Moreover, gastric and gastrointestinal digestion products have different fluorescence quenching and red shift of fluorescence peaks, and possess different conformational structures. These changes resulted in a decrease in 28.7% of the IgE binding capacity of gastrointestinal digestion products beyond that of pepsin. Moreover, gastrointestinal digestion products of glycated OVA increased significantly the proportion of Subdoligranulum, Collinsella, and Bifidobacterium. Therefore, gastrointestinal digestion products of glycated OVA altered human intestinal microbiota, reducing the risk of potential allergy.

Bovine α-lactalbumin (BLA) induced severe cow's milk allergy. In this study, a novel strategy combining ultrasonication, performed before glycation, and phosphorylation was proposed to reduce BLA allergenicity. Result showed that IgE- and IgG-binding capacities and the release rates of histamine and interleukin-6 from RBL-2H3 were reduced. Moreover, intrinsic fluorescence intensity and surface hydrophobicity were decreased, whereas glycated sites (R10, N44, K79, K108, N102 and K114) and phosphorylated sites (Y36 and S112) of BLA were increased. Minimum allergenicity was detected during BLA treatment after ultrasonic prior to glycation and subsequent phosphorylation because of considerable increase in glycated and phosphorylated sites. Therefore, the decrease in allergenicity of BLA, the effect correlated well with the shielding effect of glycated sites combined with phosphorylated sites and the conformational changes. This study provides important theoretical foundations for improving and using the ultrasonic technology combined with protein modification in allergenic protein processing.