Antioxidant/Antimicrobial Film Based on Carboxymethyl Cellulose/Gelatin/TiO2–Ag Nano-Composite

Abstract

Due to the environmental problems caused by the use of synthetic plastics in food packaging, it is necessary to replace them with biodegradable films. In this study, carboxyl methyl cellulose/gelatin composite modified with TiO2–Ag nanoparticles (CMC/Gel/TiO2–Ag) was prepared and its antioxidant, antimicrobial, mechanical, colorimetric and morphological characteristics were investigated. To evaluate the effect of gelatin percent and TiO2–Ag percentage on the film properties, a central composite design (CCD) was used. The morphology of the films was investigated by the scanning electron microscopy (SEM). SEM results showed that TiO2–Ag nanoparticles in the range of 50–100 nm were distributed among CMC polymers and gelatin. The antioxidant properties of the film showed that nanoparticles have anti-oxidant properties and can be very effective in preparing antioxidant films. The microbial test indicates antimicrobial activity of nanoparticles against Gram-negative bacteria (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. According to the mechanical results, gelatin increases the film elasticity. TiO2–Ag increases the elongation and extension of CMC film and adding of gelatin to the CMC film decrease these parameters. Adding TiO2–Ag to the film increases the maximum force to break the film (Fmax), but adding gelatin to the film decreases the Fmax. Colorimetric results showed that gelatin increased transparency and TiO2–Ag reduced the transparency. According to the results, the simultaneous increase of gelatin and TiO2–Ag, increases a* parameter. With increasing TiO2–Ag nanoparticles, the whiteness index increased. The overall results obtained from this study show that, given the antimicrobial and antioxidant properties of silver and titanium dioxide and antioxidant properties of gelatin, the CMC/Gel/TiO2–Ag film has a very important antimicrobial and antioxidant properties and can be used as an active/antioxidant packaging system.