Fabrication and characterization of nanoemulsions for encapsulation and delivery of vitexin: antioxidant activity, storage stability and in vitro digestibility.

Background: Nanoemulsions were prepared as an encapsulation and delivery system for vitexin, a poorly water-soluble antioxidant. This study evaluated how the type and concentration of the dispersed oil phase and vitexin loading impacted droplet characteristics and nanoemulsion stability. The influences of storage temperature on antioxidant activity and in vitro gastrointestinal digestion on nanoemulsion stability were also investigated.

Results: Nanoemulsions prepared at different dispersed oil concentrations showed diverse characteristics and stability. Highest stability against droplet aggregation and phase separation with small oil droplets (< 150 nm) was observed for nanoemulsions prepared using 300 g kg medium-chain triglyceride oil. These nanoemulsions are able to entrap and deliver vitexin with high encapsulation efficiency (88-90%) with no significant effect on emulsion stability. Vitexin-loaded nanoemulsions were stable during storage when refrigerated (4 °C) and at room temperature (25 °C) for up to 45 days with no effect on their antioxidant activity. Significantly delayed lipolysis rate and decreased extent of lipid digestion were observed in vitexin-loaded nanoemulsions.

Conclusions: Stable vitexin-loaded nanoemulsions were successfully produced by high-pressure homogenization using a mixture of Tween 80 and lecithin as emulsifiers. Vitexin-loaded nanoemulsions stabilized with a mixture of these two emulsifiers were effective in retaining antioxidant activity during storage and protecting vitexin from changes during gastrointestinal digestion. Our results suggested that nanoemulsions were effective vitexin delivery systems for food applications. © 2022 Society of Chemical Industry.