Formulation and characterization of food grade O/W nanoemulsions encapsulating quercetin and curcumin: Insights on enhancing solubility characteristics

Solubility of bioactive compounds (curcumin and quercetin) in aqueous phase is challenging while developing an emulsion-based delivery system. Therefore, this study was designed to enhance the solubility of curcumin and quercetin in oil-in-water (O/W) nanoemulsions using modified starch (HI-Cap-100) as an emulsifier. The effect of different processing conditions (pH, ionic strength and temperature) were investigated on the mean droplet diameter and zeta-potential over the period of 5 months. It was found that the nanoemulsions containing 5% (w/w) HI-CAP-100 along with 10% oil (w/w) yielded the most stable formulation with a mean particle size of 175.44 nm. Solubility of quercetin and curcumin was found to be maximum in nanoemulsions (2.07 and 39 times respectively) as compared to oil and water. Furthermore, stability of the emulsions under varying ionic strength (0.1-1 M NaCl) and pH (2-7) was found to be higher. Overall, it can be concluded that stability of nanoemulsions can be enhanced using natural ingredients. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.