Production of Biodegradable Films of Zein Containing Mentha asiatica Essential Oil and Copper Oxide Nanoparticles: Investigation of Physicochemical, Antimicrobial, and Antioxidant Properties
2022
Marandi, Mahdieh Shirdel | Pirsa, Sajjad | Amiri, Saber | Fazeli, Manouchehr
The objectives of the present study were to prepare an active biodegradable film based on zein-containing copper oxide nanoparticles (CuO NPs) and Mentha longifolia var. asiatica essential oil (MAEO) and to investigate the physicochemical and structural properties of the produced films. Zein films were prepared by solvent evaporation method and adding CuO NPs and MAEO in different concentrations of 0, 2.5, and 5% (w/w) and 0, 1.5, and 3% (w/w), respectively. The properties of the prepared nanocomposite including thickness, water vapor permeability, solubility, moisture absorption, moisture content, antioxidant properties, color indices and mechanical and antimicrobial properties were investigated. TGA, FT-IR, and FESEM tests were performed to investigate the interaction of film compositions, thermal stability and film surface morphology, respectively. The results showed that increasing the amount of CuO NPs led to a cohesive and smooth surface in the film, which improved the water vapor permeability in the films compared to the control film. As the percentage of CuO NPs and MAEO increased, the solubility and the moisture content decreased, but the thickness and antioxidant content of the film increased compared to the control sample (from 60.1 to 86.9%). Also, increasing the percentage of CuO NPs and MAEO led to the improvement of the mechanical properties of the film. By increasing the concentration of MAEO and CuO NPs, the amount of color indices (b* and a*) decreased and then increased. The results of antimicrobial activity against S. aureus and E. coli showed that with the addition of CuO NPs and MAEO, the diameter of the growth inhibition zone increased and the films showed high antimicrobial activity.
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