LAUSR

Abstract A factorial experiment was designed to analyze nanobiocomposite films based on kefiran–carboxymethyl cellulose carbohydrates with copper oxide nanoparticles (CuONPs) (0, 1, 1.5 and 2%) and Satureja khuzestanica essential oil (SEO) (0, 1, 1.5 and 2%) as well as their combination in order to investigate their physical, mechanical, antioxidant, antimicrobial, optical, color, dynamic mechanical thermal, and morphological properties. It was generally found that the separate addition of CuONPs and SEO to the film improved its properties. In addition, results showed that the simultaneous application of CuONPs and SEO had substantially improved the physical and mechanical properties of the films. Besides the nature of CuONPs and SEO, this effect was due to the formation of hydrogen interactions between them and the biopolymer matrix, as supported by Fourier transform infrared spectroscopy (FTIR). The simultaneous application of CuONPs and SEO had a synergistic effect on antimicrobial properties against Staphylococcus aureus and Escherichia coli bacteria and further made a significant change in color parameters and percentage of light transmission within the visible and ultraviolet light spectral ranges. The results of the dynamic mechanical thermal analysis (DMTA) showed that the films containing simultaneous combinations of CuONPs and SEO had the highest storage modulus and glass transition temperature. Results of electron microscopy images indicated that the simultaneous presence of CuONPs and SEO in films was consistent with the biopolymer matrix and distributed properly in the medium. In summary, the results of this study showed that nanobiocomposite films containing the simultaneous combination of CuONPs and SEO may be useful in food packaging.