Optimization of emulsification conditions for designing ultrasound assisted curcumin loaded nanoemulsion: Characterization, antioxidant assay and release kinetics

The present investigation was aimed to fabricate oil in water curcumin loaded nanoemulsions (Cur-NE) stabilized using Tween 20 employing ultrasonication for the encapsulation of curcumin. Effect of various process variables such as surfactant and oil concentration and sonication time intervals on the stability of curcumin nanoemulsions were studied by characterizing droplet size, polydisperity index (PDI), zeta-potential (ζ), Encapsulation Efficiency (EE), DPPH-Radicals Scavenging Activity (RSA) and turbidity of formulated nanoemulsions. Cur-NE designed using oil 5 mL/100 mL, 1.5 % surfactant and treated for 20 min of ultrasound fetched better results for droplet size (138.9 nm), PDI (0.187), ζ-potential (−20.7 mV), EE (93.6 %) and RSA (67.56 %). Physical stability of Cur-NE was investigated by exposing them to variable thermal stress conditions. Stable emulsions obtained were characterized for their morphology and in vitro release kinetics under simulated gastrointestinal conditions. The morphology results were also verified the successful designing of ultrasound assisted curcumin loaded nanoemulsion. Results of in vitro release studies suggested that the optimized Cur-NE were resistant to pepsin digestion with less than 10 % release of curcumin whereas incubation under intestinal conditions led to approximately 23 % release of curcumin indicating its slow release and increased bioavailability. Therefore, outcomes of the study demonstrated the important implications in designing of encapsulation systems for various bioactive compounds for their effective and controlled delivery in various food products.