Dynamic adsorption and stability mechanisms in Pickering emulsions co-stabilized by whey protein microgel particles and sucrose esters

Interfacial dynamic adsorption behavior of surface-active components plays a crucial role in the stability of emulsions. In this study, a combination of experimental and computational methods was used to elucidate the dynamic adsorption process at the interface of whey protein microgel particles (WPM) and sucrose esters (SE) co-stabilized Pickering emulsions (CPE), thus explaining their stability mechanisms at varying SE concentrations. Experimental results showed that increasing SE concentration reduced droplet size, enhanced WPM interfacial adsorption, inhibited droplet migration, lowered interfacial tension, and significantly improved emulsion stability. Simulation results indicated that the concentration of SE affected the pre-adsorption aggregation patterns of WPM and SE. At low SE concentrations, WPM's wettability was altered, while at high SE concentrations, SE formed aggregates with WPM. The strong adsorption of SE, the sustained anchoring of WPM at the interface (with WPM coverage ranging from 21% to 25%), and the interwoven arrangement of WPM and SE at the interface effectively lowered interfacial tension and enhanced the compactness of the interfacial layer. Higher SE concentrations reduced the mobility of WPM near the interface, thereby decreasing the overall fluidity of the interfacial film and providing a more robust spatial barrier. Additionally, SE concentration affected the equilibrium structure of the oil-water interfacial barrier, where SE competed for adsorption sites and displaced WPM from the interface, thereby increasing the interfacial membrane thickness from 15.0 Å to 19.0 Å. This research deepens our understanding of the intricate interplay between particles and surfactants in stabilizing Pickering emulsions, providing insights into potential strategies for developing more stable and efficient emulsion-based formulations through interfacial engineering.