Preparation of Curcumin Nanoemulsion and Its in Vitro Simulated Digestion Characteristics

In this study, a stable curcumin nanoemulsion delivery system was constructed using selectively hydrolyzed soy protein as the emulsifier to enhance the aqueous solubility and bioavailability of curcumin. The effect of homogenization pressure on nanoemulsions was investigated, and the particle size, zeta-potential, turbidity, microstructure, and the in vitro gastrointestinal digestion properties of nanoemulsions were determined. The solubility of curcumin was significantly (P<0.05) dependent on the type of oil, the solubility in four oil was medium chain triglycerides (MCT) > canola oil > corn oil > olive oil > soybean oil. The emulsions prepared under 50 MPa showed the smallest mean particle size (265.00±4.14 nm), larger zeta-potential (-30.77±0.71 mV), and the lowest turbidity. The curcumin-loaded nanoemulsions prepared with rapeseed oil and MCT could resist pepsin digestion and maintain a certain interfacial tension in the stomach to keep the emulsion in its original form, while being digested in the small intestine with a 60% release rate of free fatty acids. The bioavailability and retention of curcumin decreased significantly with the increasing in the ratio of canola oil to MCT. Among them, the emulsions formed with rapeseed oil:MCT=3:7 oil phase possessed almost the same bioavailability and retention of curcumin as those with pure MCT oil phase, close to 70%. The study would provide guide for the design of delivery systems to encapsulate and release high lipophilic functional components.