High internal phase emulsions stabilized by polyphenol-mediated Moringa seed protein for β-carotene encapsulation: Enhanced stability and bioaccessibility.

In this study, Moringa oleifera seed protein (MOSP) served as the raw material, while three polyphenols-epicatechin (EC), epigallocatechin gallate (EGCG), and tannic acid (TA)-were incorporated for modification to produce a high internal phase emulsion (HIPE). For each of the three polyphenols, the optimal addition level was around 15 μg per 1 mg of MOSP. The inclusion of polyphenols resulted in the interfacial tension being at the oil-water interface was significantly diminished, decreasing from 10.22 mN/m to 5.43 mN/m, with the emulsifying activity index (EAI) of MOSP-TA reaching 72.50 m2/g. Molecular dynamics simulations demonstrated that the MOSP-polyphenol complex rapidly and stably adsorbed at the oil-water interface within 30 ns, thereby reducing interfacial formation energy. The HIPEs prepared with MOSP-TA exhibited the smallest increase in droplet size after 30 days of storage and after heating, with the mean diameter increasing from 234.67 μm to 352.33 μm and from 108.33 μm to 191.33 μm, respectively. The loading capacity of β-carotene using MOSP-TA-stabilized HIPE can reach as high as 81%. This HIPE protects β-carotene against thermal and UV degradation. In in vitro simulated digestion experiments, HIPE significantly slows the release of free fatty acids, which aids in regulating functional factors and allows them to maintain their efficacy. The bioaccessibility of β-carotene can reach a maximum of 40%. In conclusion, MOSP-TA serves as an effective emulsifier with promising applications in the formulation of high internal phase emulsions. This study presents a novel strategy for delivering hydrophobic functional factors that exhibit environmental sensitivity and low bioaccessibility within food systems.