Effect of chitosan/essential oils/silver nanoparticles composite films packaging and gamma irradiation on shelf life of strawberries

The present study illustrates the synthesis of silver nanoparticles (AgNPs) using tyrosine as a reducing agent and preparation of chitosan (CHI) based films by blending essential oils (EOs) and synthesized AgNPs. The prepared CHI-EOs-AgNPs composite films were used for the packaging of strawberries in the presence or absence of gamma irradiation. The composite films were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, color property, tensile properties, and water vapor permeability. The scanning electron microscopy result showed the smooth surface of the composite films, whereas Fourier transform infrared spectroscopy results exhibited a change in the structure of CHI after blending EOs and AgNPs. The flexibility of the composite films increased after the addition of EOs, but tensile strength increased after blending AgNPs. The water vapor barrier property of composite films has not changed upon blending EOs or AgNPs. The CHI-EOsAgNPs composite films exhibited strong antimicrobial activity against Escherichia coli, Listeria monocytogenes, Salmonella Typhimurium, and Aspergillus niger. The effects of packaging and ?-irradiation on the shelf life and quality of packaged strawberries during storage were evaluated by the weight loss, firmness, decay (%), color, anthocyanin, and total phenol content. All composite films exhibited lower weight loss than control samples, and ?-irradiation reduce the firmness and decay during 12 d of storage.