Retardation of curcumin degradation under various storage conditions via turmeric extract-loaded nanoemulsion system

Abstract The stability of encapsulation systems in foods has often been overlooked in the literature. Thus, in this study, turmeric extract-loaded nanoemulsion powder (TE-NEP) was prepared by ultrasonication and spray drying. The physicochemical properties of the TE-NEP were investigated after re-dispersion in several food simulants including distilled water, ethanol, and solutions with various pH and ionic strengths. The diameter of the re-dispersed TE-NEP notably increased in ethanol concentrations >10%. Furthermore, the zeta potential significantly increased as the pH increased, but decreased as the NaCl concentration increased. The stability of the TE-NEP was also evaluated by determining the curcumin retention rate. In all cases, the retention rate of the TE-NEP was higher than that of the native curcumin used as a control. The retention rate of the TE-NEP remained stable for 14 days of storage, but decreased afterward. Nevertheless, the retention rate remained high (>83%) in all cases except pH > 8. Therefore, the TE-NEP would be applicable in food products with various ethanol and salt concentrations, as well as products with pH in the acidic and neutral range.