Construction and characterization of Pickering emulsions stabilized by soy protein hydrolysate microgel particles and quercetin-loaded performance in vitro digestion

Food-grade Pickering emulsions stabilized by protein microgel particles have received increasing attentions owing to their potential applications in the food industry. Herein, soy protein hydrolysate microgel particles (SPHMs) produced at various pH (3, 5, 7, and 9) with and without ultrasonication were used to stabilize Pickering emulsions. Compared with those prepared using ultrasonication at pH 3–7, SPHMs prepared using ultrasonication at pH 9 showed excellent amphiphility at the oil–water interface and a superior ability to reduce interfacial tension. The Pickering emulsion stabilized by the latter SPHMs displayed a small particle size and a high net charge on the droplet surface, formed a dense honeycomb network interfacial layer with high viscoelasticity and adsorbed protein content, and experienced no visually detectable creaming during storage for 21 days, i.e., exhibited optimum colloidal stability. Furthermore, the above emulsion featured a quercetin encapsulation efficiency of 89.45 % and was capable of sustainable release, achieving a low free fatty acid release efficiency of 61 % and a relatively high quercetin bioaccessibility of 65 % in in vitro simulated digestion experiments. Thus, this work inspires the use of SPHMs in emulsion-based functional foods.