Improving antioxidant and antimicrobial properties of curcumin by means of encapsulation in gelatin through electrohydrodynamic atomization

Abstract

Curcumin is a polyphenol with a wide range of biological properties, including antioxidant and antimicrobial activity; however, its use as a food preservative is limited because of its insolubility in water. The present work is an attempt to overcome this problem by means of matrix encapsulation of curcumin in gelatin through electrohydrodynamic atomization (EHDA). Compact spherical gelatin particles ranging from few nanometers to more than 1 μm in diameter loaded with 10% (w/w) curcumin were successfully obtained, and the encapsulation efficiency being close to 100%. Fluorescence microscopy indicated that the curcumin was homogeneously distributed in the particles, while modulated differential scanning calorimetry analysis showed that the curcumin was intimately mixed with gelatin polymer, and a complete loss of curcumin crystallinity was observed in the solid dispersion. Furthermore, the UV–visible spectrum of dissolved/dispersed particles showed a shift of the maximum absorbance of curcumin toward lower wavelengths, indicating gelatin–curcumin interactions. The water solubility of curcumin increased 38.6-fold after it had been encapsulated in gelatin microparticles. With regard to antioxidant properties, they increased when blended with gelatin compared with commercial curcumin powder. Although antibacterial activity of raw curcumin was negligible at concentrations up to 100 mg/ml, gelatin-encapsulated curcumin at 4 mg/ml reduced the microbial population by 2.08, 1.67, 2.70, and 2.18 log counts (CFU/ml) for L. monocytogenes, S. enterica, S. aureus, and E. coli, respectively. Accordingly, it was proved that encapsulation of curcumin in gelatin particles by EHDA greatly improved its antioxidant and antimicrobial properties, thus broadening its potential use as a food preservative.