Preparation of chitosan/zinc oxide/Melissa officinalis essential oil nano-composite film and evaluation of physical, mechanical and antimicrobial properties by response surface method
The use of biodegradable films for releasing antimicrobials into food packaging is an active packaging type in the food industry. In this study, an antibacterial film was produced based on the chitosan biopolymer, in which zinc oxide (ZnO) particles (0, 1 and 3% (W/V)) and Melissa essential oil (0, 0.25 and 0.5% (W/V)) were used for the enhancement of the biopolymer properties based on the central composite design (CCD). Physical, color, antimicrobial and mechanical properties including tensile strength (TS) and strain to break (STB), FT-IR, XRD and surface morphology of chitosan/Melissa essential oil/ZnO (CS/MEO/ZnO) film were investigated. The results of surface morphology showed that the sizes of zinc oxide particle in the polymer structure are in the nanometer size (40–80?nm). Increasing the concentration of zinc oxide nanoparticles and Melissa essential oil increased the TS of films and reduced water solubility and water vapor permeability (WVP). The results of color analysis showed that by increasing the concentration of zinc oxide, opacity was increased. Increasing the concentration of Melissa essential oil increased the transparency of film samples. The results of antimicrobial properties showed that increasing the concentration of zinc oxide and Melissa essential oil increased the antibacterial properties of composite film. The overall result of this study showed that the resulting composite film can be used as a new antimicrobial biodegradable composite film in food packaging industry.