Multiplex comparison of the digestibility of allergenic and non-allergenic proteins in rice grains by in vitro digestion

To evaluate the digestibility of rice allergenic and nonallergenic proteins under the influence of the rice grain matrix, rice powder was subjected to in vitro digestion by simulated gastric fluid (SGF) and simulated intestinal fluid (SIF). Rice proteins were extracted from the liquid and the solid phases and analysed by SDS–PAGE, and rice allergenic proteins were detected by a multiplex immunodetection method. The digestion of soluble proteins was carried out in both liquid and solid phases, while that of insoluble proteins only occurred in the solid phase. In SGF digestion, rice proteins were more quickly digested at pH 1.2 than at pH 2.0 or 2.5. Moreover, the digestibility of five kinds of rice allergenic proteins was influenced by pH level, heat processing, starch matrix, solubility, and protein properties, on a case-by-case basis. On the other hand, all detected rice allergenic proteins and non-allergenic proteins were rapidly digested in SIF.