Excipient foods have compositions and structures specifically designed to improve the bioaccessibility of bioactive agents present in other foods coingested with them. In this study, an excipient emulsion was shown to improve the solubility and bioaccessibility of curcumin from powdered rhizome turmeric (Curcuma longa). Corn oil-in-water emulsions were mixed with curcumin powder, and the resulting mixtures were incubated at either 30 °C (to simulate a salad dressing) or 100 °C (to simulate a cooking sauce). There was an appreciable transfer of curcumin into the excipient emulsions at both incubation temperatures, but this effect was much more pronounced at 100 °C. The bioaccessibility of curcumin measured using a simulated gastrointestinal tract model was greatly improved in the presence of the excipient emulsion, particularly in the system held at 100 °C. This effect was attributed to the higher initial amount of curcumin solubilized within the oil droplets, as well as that solubilized in the mixed micelles formed by lipid digestion. This study highlights the potential of designing excipient food emulsions that increase the oral bioavailability of lipophilic nutraceuticals, such as curcumin.
Keywords: bioaccessibility; curcumin; excipient food; nanoemulsion; nutraceutical.