Curcumin-loaded nanoemulsions produced by the emulsion inversion point (EIP) method: An evaluation of process parameters and physico-chemical stability

Curcumin is a natural antioxidant dye that has a wide spectrum of biological activities (e.g., anti-cancer, anti-hypertensive, anti-inflammatory and neuroprotective activities), and there is a high interest within the food industry to increase its use as a natural additive. However, due to its high hydrophobicity, it is difficult to incorporate into aqueous formulations and its bioavailability can be severely decreased. Lipid-based encapsulation systems such as nanoemulsions can help to overcome both of these drawbacks. In this study, curcumin-loaded nanoemulsions were produced by the emulsification inversion point method, for which some of the operational parameters were optimized. The most stable formulations were composed of 20% soybean oil, 10% Tween 80 and 20% glycerol and were produced with an anchor blade impeller operating at 300 rpm; this combination of parameters resulted in 0.07% encapsulation of the curcumin. After 60 days, 70% of the initial amount of curcumin remained in the nanoemulsions, which is a promising result when compared with those of other lipid-based encapsulation systems. The data also indicated that the catastrophic phase inversion occurred due to the formation of multiple o/w/o emulsions.