Effect of chitosan-gelatin film incorporated with ethanolic red grape seed extract and Ziziphora clinopodioides essential oil on survival of Listeria monocytogenes and chemical, microbial and sensory properties of minced trout fillet

• Chitosan-gelatin film enriched with ZEO and GSE improved the shelf life of fish fillet.
• Combination of ZEO and GSE led to strong antibacterial activity.
• Chitosan-gelatin film could be used as an excellent type of active packaging.

The aim of the present study was to evaluate the effects of chitosan-gelatin film incorporated with grape seed extract (GSE) (1 and 2%) and Ziziphora clinopodioides essential oil (ZEO) (1 and 2%), separately and in combination, on survival of Listeria monocytogenes and shelf life extension of minced trout fillet during refrigerated storage (4 ± 1 °C) over a period of 11 days. The control and wrapped fillet samples were analyzed for chemical (PV and TVB-N), microbial (Total mesophilic and psychrotrophic bacteria, Pseudomonas spp., P. fluorescens, Shewanella putrefaciens, lactic acid bacteria and Enterobacteriaceae family) and sensory properties (odor, color and acceptability). The GC-MS analysis of the essential oil components revealed that carvacrol (65.22%) and thymol (19.51%) were the most representative components of the essential oil. In comparison with control group, fish spoilage was significantly delayed in samples wrapped in chitosan-gelatin film containing different concentrations of GSE and/or ZEO (P < 0.05). The lowest bacterial growth, PV and TVB-N content were obtained in fish samples wrapped in film containing ZEO2%+GSE2%. The fillets treated with ZEO2%+GSE1% and ZEO2%+GSE2% had the best organoleptic properties. Based on our findings, the antibacterial activity of chitosan-gelatin film incorporated with GSE and ZEO enhanced the shelf life of fish fillet.