Synergistic effect of nano-ZnO and Mentha piperita essential oil on the moisture sorption isotherm, antibacterial activity, physicochemical, mechanical, and barrier properties of gelatin film

This study aimed to evaluate the synergistic effect of nano-ZnO (ZnO-N) and Mentha piperita essential oil (MEO) on the functional and antibacterial properties of bovine gelatin bionanocomposite film. A mixture of ZnO-N (1%, 3%, and 5%) and MEO (1%, 2%, and 3%) was incorporated into gelatin films. The physicochemical, mechanical, antimicrobial, and barrier properties of the films were explored. Results demonstrated that adding combined ZnO-N and MEO to films lead to decreased moisture content, solubility, water-absorption capacity, water vapor and oxygen permeability, and elongation. However, the thickness, tensile strength, Young's modulus increased. Incorporating the combination of ZnO-N and MEO into films also reduced the monolayer and free-water content in the equilibrium-adsorption isotherm and shifted the isotherm to lower moisture content. These bionanocomposites showed good antibacterial activity against Escherichia coli O157:H7. In summary, a synergistic effect was observed by incorporating ZnO-N and MEO in active gelatin films.