Extraction of rosemary essential oil and its use in the preparation of biocomposite based on mucilage film of fenugreek seeds and eggplant skin powder containing copper nanoparticles.

Adding copper nanoparticles and rosemary essential oil can improve the structural and mechanical properties of films based on fenugreek seed mucilage and eggplant skin powder. The aim of this study was to prepare edible films based on mucilage of fenugreek seeds and eggplant skin powder containing copper nanoparticles (0, 2, 4% w/w) and rosemary essential oil (0, 4, 8% w/v). Edible films were prepared based on mucilage of fenugreek seeds and eggplant peel powder, and copper nanoparticles (0, 2, 4%) and rosemary essential oil (0, 4, 8%) were added to it. The structural and mechanical properties of the prepared films were investigated. According to the obtained results, increasing the amount of copper nanoparticles and rosemary essential oil in the film decreased the mechanical properties of the films. According to the obtained results, increasing the amount of copper nanoparticles and rosemary essential oil in the film decreased the mechanical texture of the films. X-ray diffraction (XRD) analysis showed that copper nanoparticles were physically combined with fenugreek seed mucilage polymer and eggplant skin powder, resulting in the strengthening of the crystal structure. Fourier transform infrared (FTIR) results confirmed the physical presence of copper nanoparticles in the polymer matrix. The results of the scanning electron microscope (SEM) showed that the surface morphology of the nanocomposite film is heterogeneous compared to fenugreek seed mucilage and eggplant skin powder. Exposure of the prepared detector film to different pHs led to the change of the color of the films from red to yellow. These color changes of the films were consistent with the color changes of the anthocyanin solution. The addition of copper nanoparticles and rosemary essential oil to edible films based on fenugreek seed mucilage and eggplant skin powder improved the Fourier transform infrared (FTIR) of the films, and also weakened the mechanical properties.