Enhanced Curcumin Bioavailability through Nonionic Surfactant/Caseinate Mixed Nanoemulsions

The potential of heterogeneous systems like oil-in-water (O/W) nanoemulsions is exploited as an oral delivery system for curcumin, a natural lipophilic compound with numerous health benefits. Two types of O/W nanoemulsions, one stabilized by sodium caseinate (Cas-O/W), a surface-active and emulsifying protein, and the other stabilized by a blend of caseinate and Tween 20 (Mix-O/W), were loaded with the bioactive compound and tested through a simulated gastrointestinal digestion process to evaluate their effects on delivering of curcumin. It was first demonstrated that the amount of curcumin solubilized through Mix-O/W nanoemulsion was higher than that in Cas-O/W nanoemulsion. Cas-O/W nanoemulsions, indeed, at their best, solubilized about 55 µg/mL of curcumin while Mix-O/W nanoemulsions reached a curcumin concentration around 180 µg/mL. Furthermore, for both the systems an increase of curcumin loading capacity was recorded with the rise of incubation temperature. Finally, after the in vitro simulated digestion process, the potential curcumin bioavailability was evaluated and the data suggested that Mix-O/W nanoemulsions provided more than twice the amount of curcumin compared to Cas-O/W nanoemulsions. On balance, the outcomes of this investigation demonstrated that the mixed emulsifier system offered a higher amount of lipophilic compound with a low fat intake compared to nanoemulsions stabilized by sodium caseinate. Practical Application: The outcomes of this study allow the recognition of the protein/surfactant-stabilized nanoemulsions as a suitable solution to deliver curcumin. The nanoemulsions proposed here provide a high intake of curcumin, a lipophilic compound, with low fat content. The use of such delivery systems helps to overcome limits in oral bioavailability related with the scarce solubility of some compounds in food preparations and beverages.