Properties and microstructure of pickering emulsion synergistically stabilized by silica particles and soy hull polysaccharides

A soy hull polysaccharide (SHP) and hydrophilic silica particle system has been proven to be effective emulsifiers for forming and stabilizing food emulsions. Adsorption of the SHP molecules onto the surface of the silica particles improved the particle wettability, resulting in greater interfacial stability at the oil-water interface, as shown by scanning electron microscopy, three-phase contact angle and interfacial intension analysis. The properties of the emulsion prepared with silica particles in the presence of SHP at different concentration were also investigated to explore the effect of polysaccharide–particle interactions on emulsion stabilization. As the SHP concentration increased, we observed a synergistic effect of reducing the interfacial tension (13 mN/m) and increasing the interface particle adsorption rate (66%) due to the complexation of SiO2-SHP by hydrogen bonding in the bulk and at the interface. Correspondingly, at high SHP concentrations (2%–4%), the formation of a colloidal gel in the continuous aqueous phase provided the emulsion with a yield stress, thereby giving it a gel-like and thus quiescent behavior under low-shear conditions. Moreover, quiescent emulsion gels were obtained with d4,3 of about 12 μm, uniform appearance and microstructure, excellent storage stability (TSI<1.5, 30d), and good rheological properties including higher gel strength and viscosity. These results indicated a synergistic stabilization upon SHP addition and the formation of a hydrogel network in the continuous phase as well as around the droplet surfaces.