Phenolic composition of Hemerocallis citrina Borani and enhancement of release and antioxidant efficacy through an emulsion-based delivery system during in vitro digestion

Hemerocallis citrina (Huang hua cai in Chinese), known for its rich polyphenolic content, faces challenges in practical applications due to the instability of these compounds in the intestinal environment. This research addresses these challenges by encapsulating the polyphenols in a soybean protein isolate emulsion, enhancing their bioavailability and stability. The interactions between the polyphenols and soy protein were elucidated using molecular docking. The analysis identified 6 phenolic acids and 71 flavonoids. After two hours of simulated intestinal digestion, there were significant increases in particle size, ζ-potential, and the concentrations of polyphenols and flavonoids in the emulsion. Antioxidant activity, measured by FRAP and ABTS assays, showed progressive enhancement during digestion. Notably, intestinal digestion significantly increased the release and efficacy of flavonoids. The emulsion system markedly influenced the antioxidant capacity of the phenolic compounds. Molecular docking revealed quercetin as the most favorably binding compound, followed by naringenin, isorhamnetin, 4-hydroxybenzoic acid, isoquercitrin, and rutin. These findings are vital for optimizing Hemerocallis citrina polyphenolics and enhancing their stability and functionality in various applications.