Physicochemical properties of gelatin/silver nanoparticle antimicrobial composite films

Active nanocomposite films were prepared by blending aqueous solutions of gelatin with different concentrations of silver nanoparticles (AgNPs) using a solvent casting method. Formation of silver nanoparticles in the solution and films was confirmed with the surface plasmon resonance (SPR) band at 400-450 nm, measured by UV-vis absorption spectroscopy. The incorporation of AgNPs slightly affected the physical and mechanical properties of the films. Increase in the concentration of AgNPs resulted in a substantial decrease in water vapour permeability (WVP) and tensile strength (TS) of the gelatin films. Energy dispersive X-ray (EDX) spectroscopy and X-ray diffraction (XRD) analysis confirmed the presence of elemental silver and crystalline structure of the AgNPs in the gelatin film. Microscopic surface structure and thermal properties of the films were also examined by FE-SEM and thermogravimetric analysis. Gelatin/AgNPs nanocomposite films exhibited strong antibacterial activity against food-borne pathogens. Gelatin/AgNPs nanocomposite films are expected to have high potential as an active food packaging system to maintain food safety and to extend the shelf-life of packaged foods.