The effect of pH on the stabilization and digestive characteristics of soybean lipophilic protein oil-in-water emulsions with hypromellose

The development of functional foods requires a detailed understanding of the behavior of lipophilic protein (LP) in the presence of emulsion stabilizers at different pH conditions. In this study, we examined the interaction between hydroxypropyl methylcellulose (hypromellose, HPMC) and soybean lipophilic protein. To that end, we examined the stabilities of LP-HPMC emulsions at pH 3, 5, and 7, as well as the oil-release behavior of LP-HPMC emulsions during digestion. Fluorescence data showed that HPMC binds to LP with quenching at a single binding site that did not change with pH. Atomic-force microscopy, emulsification, and oxidation-stability analyses showed that HPMC improves the pH stability of the LP-HPMC emulsions, while simulated in-vitro digestion experiments showed that added HPMC delayed the release of lipids to varying degrees. The results of this study will aid in the development of emulsion-based functional foods, pharmaceutical carriers with controlled-release or sustained-release functional ingredients.