The aim of current study was to investigate the antimicrobial effect of gum essential oil of Pistacia atlantica (wild pistachio) tree (GEO) and design a new film based on polypropylene polymer coated with silica nanoparticles and GEO. The antimicrobial activity of the packaging film was evaluated with or without milk on Staphylococcus aureus, Salmonella enterica, Escherichia coli, and Listeria monocytogenes during 35 days. The results showed that GEO has significant antibacterial properties. It was most effective on Salmonella enterica, while its effect on Listeria monocytogenes was the weakest. Antimicrobial activity of the film without milk showed no significant differences among the different sizes of nanoparticles used (0.05, 0.025, and 0.051 g) (p ≥ .05). It can be concluded that polypropylene incorporated with GEO and silica nanoparticles active film had antimicrobial properties up to 35 days, while using with milk or without milk. Therefore, this type of packaging is effective to enhance the shelf life of milk.

Background: Staphylococcus aureus, Salmonella enterica, Escherichia Coli (E. Coli) and Listeria monocytogenes are considered as important foodborne pathogens. Pistachia atlantica sub sp. Kurdica, called wild pistachio, has been known as an antimicrobial compound. The aim of this study was to determine the antimicrobial activity and chemical composition of this essential oil (EO) on some of foodborne pathogens. Methods: The EO of Pistachia atlantica was obtained by hydro-distillation and analyzed by GC-MASS. The antibacterial effects of Pistachia atlantica were evaluated at two concentrations of 10 and 15 µL against Staphylococcus aureus, E. Coli, Salmonella enterica, and Listeria monocytogenes using disk diffusion method. The analysis was done by SPSS. Results: In the current study, α-pinene (92.5%) and ß-pinene (1.62%) were the main components of Pistachia atlantica EO. The EO was most effective on Salmonella enterica, whereas, its effect on Listeria monocytogenes was the weakest. The results showed a significant difference in reducing Salmonella enterica in comparison to others (P < 0.05). Conclusion: The EO has inhibitory effects on the studied bacteria. Therefore, this EO can be used as a natural preservative to extend the shelf life of foods.