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

[Display omitted] •Solubility of curcumin and quercetin in O/W nanoemulsions•O/W nanoemulsions provided higher stability to curcumin and quercetin•Stability of encapsulated bioactives can be enhanced up to 5 months of storage period 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 ζ-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.