Encapsulation of bioactive compounds in nanoemulsion- based delivery systems

Encapsulation into nanoemulsion-based delivery systems of bioactive compounds characterized by low solubility in aqueous phase, represents an effective approach to improve the dispersion of the bioactives into food products, to protect them against degradation or interaction with other ingredients, to reduce the impact on organoleptic properties of the food and to improve their bioavailability. The aim of the present work is the fabrication of nanoemulsions, based on natural food ingredients, to be used as delivery systems of two different bioactive compounds, resveratrol and curcumin, with the ultimate goal of improving the antioxidant and/or antimicrobial activities of the encapsulated compounds. A preliminary screening study of the optimal emulsion ingredients was carried out through the construction of a pseudo-ternary phase diagram of kinetic stability. The formation of very fine emulsions in the nanometric range (< 200 nm) was achieved by high pressure homogenization treatment, choosing those formulations containing small amounts of emulsifier, in order to minimize the impact on the organoleptic properties. Resveratrol (0.01% wt) was encapsulated in peanuts oil-based nanoemulsions, using different emulsifiers, such as soy lecithin and sugar esters. Curcumin was encapsulated in stable solid fat nanoemulsions, using stearic acid as lipid phase, up to 0.1% wt concentration. The nanoemulsions were characterized in terms of physical stability of the mean droplet size (dynamic light scattering) and chemical stability of the encapsulated bioactive compounds (HPLC and UV-Vis spectra analysis) upon accelerated ageing conditions. The effectiveness of the delivery systems was evaluated in terms of antioxidant activity of the encapsulated compounds.