Preparation of New Nanocomposite Film For Controlling Listeria Monocytogenes and Staphylococcus Aureus in Raw Rainbow Trout Fillet

Objective(s): this study was aimed to evaluate the effect of chitosan-zinc oxide (ch-zno) film containing pomegranate peel extract (ppe; 0.5, 1 and 1.5%) on survival of listeria monocytogenes and staphylococcus aureus in raw rainbow trout fillets during refrigerated storage for 12 days. methods: total polyphenolic contents of ch-zno films containing different concentrations of methanolic ppe were determined with folin-ciocalteu reagent. in order to enumerate the inoculated pathogenic bacteria in raw rainbow trout fillets, palcam listeria selective agar (l. monocytogenes, incubated at 30 °c for 48 h) and baird parker agar (s. aureus, incubated at 37 °c for 48 h) were used. results: total phenolic content of ch-zno enriched with ppe was recorded to be 72-139 mg gallic acid/g film. for un-treated samples, the initially recorded population of 5 log cfu/g of l. monocytogenes and s. aureus were reached 5.36 and 3.03 log cfu/g at the end of designated study period, respectively. there were significant differences between samples packed with ch-zno films enriched with different concentrations of ppe (0.5, 1 and 1.5%) and untreated ones (p < 0.05). in both samples treated with 1 and 1.5% ppe, the final bacterial population were reached below 1 log cfu/g at the end of storage period. conclusions: the results of the present study indicate a potential use of ch-zno film enriched with ppe as an effective type of antimicrobial packaging to inhibit the growth of l. monocytogenes and s. aureus in raw rainbow trout fillets.