Impact of oil volume fraction on stability of Pickering emulsion prepared by silica particles and soy hull polysaccharides

Abstract

Soy hull polysaccharides (SHP) and silica particles synergistically prepare stable Pickering emulsions. The effect of oil volume fraction (ø, 20 %–80 %) on the stability of the SiO₂-SHP Pickering emulsions was investigated. The results suggested that SiO₂-SHP constructed a dense polymer-particle-composite network in the continuous phase, promoting emulsion stability. Increasing ø enhances viscosity and elastic modulus by densifying the oil phase, demonstrating that the increase of the oil phase led to a closer filling and a greater degree of interaction between the dispersed phase droplets, thereby enhancing the gel network strength of the emulsion. At lower ø (20 % and 30 %), non-adsorbed SHP at oil droplet interfaces leads to depletion flocculation. At ø of 40 %–60 %, emulsion droplet presented circular shapes with clear edges. Particularly, the emulsion at ø of 70 % performed excellent storage stability (Turbiscan stability index, TSI<7.5, 60 d), where SiO₂-SHP acts as both surface adsorbent and structuring agent for the dispersed phase. However, at ø of 80 %, the TSI value of the emulsion slightly increased due to insufficient particle concentration and cannot completely cover the droplet surface, resulting in bridging flocculation and affecting emulsion stability. This investigation provides a theoretical foundation for practical applications and further research on Pickering emulsions at varying ø.