Effects of steam explosion treatment on the physicochemical properties and biological activities of okara‐derived soluble dietary fibre

Summary Okara is the by‐product of soybean during processing, which is rich in dietary fibre. In this study, the effects of steam explosion (SE) treatment on the physicochemical properties and biological activities of soluble dietary fibre (SDF) from okara were investigated. Results showed that SE increased the water‐holding capacity, oil‐holding capacity, swelling capacity, water solubility, foaming ability, foaming stability, emulsifying activity and emulsion stability of SDF. The structure of okara‐derived SDF was changed after SE treatment, and the surface was poriferous, rough and collapsed. SDF from okara modified by SE exhibited significantly higher glucose adsorption capacity, cholesterol adsorption capacity and antioxidant activity manifested by the increase in DPPH and ABTS‐radical scavenging activity as well as ferric ion‐reducing antioxidant power. In vitro colonic fermentation and 16S rDNA sequencing showed that SE treatment up‐regulated the short‐chain fatty acids (SCFAs) concentrations and increased diversity of gut microbiota. Moreover, SE treatment increased the relative abundance of specific beneficial bacteria including Lactobacillus , whereas decreased the relative abundance of Firmicutes , Enterococcus , Escherichia‐Shigella and Proteus . In conclusion, these results highlight the potential of SE in improving the physicochemical and functional properties of okara‐derived SDF and promoting its future application.