Correlation of Emulsion Structure with Cellular Uptake Behavior of Encapsulated Bioactive Nutrients: Influence of Droplet Size and Interfacial Structure

In this study, an in vitro Caco-2 cell culture assay was employed to evaluate the correlation between emulsion structure and cellular uptake of encapsulated beta-carotene. After 4 h of incubation, an emulsion stabilized with whey protein isolate showed the highest intracellular accumulation of beta-carotene (1.06 mu g), followed by that stabilized with sodium caseinate (0.60 jag) and Tween 80 (0.20 mu g), which are 13-, 7.5-, and 2.5-fold higher than that of free beta-carotene (0.08 mu g), respectively. Emulsions with small droplet size (239 +/- 5 nm) showed a higher cellular uptake of beta-carotene (1.56 mu g) than emulsiond with large droplet size (489 +/- 9 nm) (0.93 mu g) (p < 0.01). The results suggested that delivery in an emulsion significantly improved the cellular uptake of beta-carotene and thus potentially its bioavailability; uptake was closely correlated with the interfacial composition and droplet size of emulsions. The findings support the potential for achieving optimal controlled and targeted delivery of bioactive nutrients by structuring emulsions.