Stability and digestion characteristics of pickering high internal phase emulsions formed by acid-induced soy lipophilic protein, β-conglycinin, and globulin

Soy-protein-stabilized high internal phase emulsions are widely used in the food industry. However, this food type cannot be suitably absorbed and utilized by the human body. In this study, we successfully prepared acid-treated soy lipophilic protein- (LP), β-conglycinin- (7S), and globulin (11S)-stabilized high internal phase Pickering emulsions (HIPPEs). The effects of pH on the structure and properties of LP, 7S and 11S were also determined. Fourier-transform infrared spectroscopy showed that acid treatment changed the secondary structure of the protein. In addition, particle size, zeta potential, and emulsification performance measurements revealed that at pH 2, the three proteins had the smallest sizes, highest charges, and best emulsification stability. Microstructure and rheology analyses showed that at pH 2, protein concentration of 1.5%, and oil-phase volume fraction of 80%, the three proteins formed HIPPEs with gel-like network structures. Among these, LP-stabilized HIPPE had the most stable structure and afforded the best oxidation stability. Simulated in vitro digestion experiments showed that the HIPPE prepared by LP under acidic conditions had good stability in gastric juice and delayed the lipid release. These results can be useful for the development of emulsion-based functional food ingredient delivery systems for targeted and sustained release of nutrients.