Electrospray Production of Curcumin-walnut Protein Nanoparticles

Electrospray technique was applied to produce nanoparticles (NPs) from walnut protein isolate (WPI) in order to encapsulate curcumin. The optimized condition for the production of the WPI NPs was WPI concentration of 3.5%, a solvent mixture of deionized water: 2-propanol (2:1, v/v), electrospraying at a fixed distance, voltage and flow rate including 17.5 cm, 20 kV and 0.09 mL/h, respectively. The ratio of curcumin to WPI was 1:100 (w/w), and the encapsulation efficiency was around 61.5%. The addition of curcumin to WPI solution affected the size, form and surface properties of the electrosprayed NPs. FESEM, HRTEM, AFM, XRD, FT-IR and fluorescence spectroscopy, were applied for the characterization of the produced NPs via electrospraying. The in vitro study revealed that release of curcumin was limited in the stomach due to the protective effect of WPI NPs. In the small intestine, WPI particles were hydrolyzed and curcumin was released. Furthermore, the antioxidant activity of curcumin-WPI NPs after in vitro digestion was significantly higher than WPI NPs due to the bioactive peptides released from WPI NPs. It can be concluded that WPI NPs could act as a unique food-grade carrier to boost the solubility of curcumin.