Etching–Hydrophobicity Modification of Soybean Dreg Insoluble Dietary Fibers and Their Pickering Emulsion Stabilization Mechanisms

Soybean dregs, one of the main byproducts of traditional soybean processing, are rich in insoluble dietary fiber (IDF), which possesses high mechanical strength and thermal stability. After surface reconstruction treatment, they have the potential to serve as a Pickering emulsion stabilizer, as these properties enable the particles to maintain their structural integrity at the oil–water interface. In this research, high-purity soybean dreg insoluble dietary fibers (HPSIDFs) were modified by alkaline H2O2, with oleic acid (OA) modified in a green synergistic modification. The surface of HPSIDF was etched to increase the reaction sites for subsequent hydrophobic modification, which enhanced the emulsification properties. Finally, the performance of the particles in Pickering emulsions and the emulsification mechanism were analyzed. The absolute value of the ζ-potential of the hydrophobically modified high-purity soybean dreg insoluble dietary fiber (O-HPSIDF) increased from 15.87 mV to 37.27 mV. The stability of the Pickering emulsion stabilized by O-HPSIDF was greatly enhanced; the droplet size of the emulsion decreased; the distribution was more uniform. The emulsifier particles formed a network structure at the interface, which imparted considerable mechanical strength to the emulsion, as evidenced by the increased storage modulus and viscosity.