Encapsulation of curcumin in zein/ caseinate/sodium alginate nanoparticles with improved physicochemical and controlled release properties

Curcumin-loaded zein nanoparticles that have a stabilized dual coating shell structure in combination with sodium caseinate (SC) and sodium alginate (SA) were fabricated and characterized. The mass ratio of each component, including the zein final concentration, the mass ratio of zein to SC, and the mass ratio of SC to SA influence the physicochemical properties of the nanoparticles. The fluorescence spectrum confirmed that curcumin was encapsulated in the composite nanoparticles with an increase in the mass ratio of curcumin to zein, and the encapsulation efficiency of curcumin decreased. When coated with SA, there was a significantly improved encapsulation efficiency. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and surface hydrophobicity measurements indicated that hydrophilic SC and SA adsorbed on the surface of curcumin-loaded zein nanoparticles via electrostatic interactions to improve their water solubility. Encapsulation of curcumin in the composite nanoparticles not only significantly improved the photochemical stability and made it more effective in scavenging the 1, 1-diphenyl-2-picrylhydrazyl free radical (DPPH●) compared with vitamin C but also provided controlled release under simulated gastrointestinal conditions. Therefore, SC-SA-stabilized zein nanoparticles are effective for improving the water solubility, photochemical stability and antioxidant activity of curcumin, and the prepared composite nanoparticles are expected to be used as a delivery carrier for chemically unstable hydrophobic active compounds in food and pharmaceutical industries.