Antimicrobial Effect of Gel-Type Nanoemulsion of Chitosan Coating Containing Essential Oils of Zataria multiflora and Bunium persicum on Pseudomonas Artificially Inoculated onto Salmon Fillets

Background and objectives: Chitosan is a preservative that is commonly used in food packaging due to forming a film with antimicrobial activity. Many antimicrobial agents have been used to control the growth of different bacteria, fungi and yeasts in food products using chitosan coating. The present research was conducted to examine inhibitory effects of a coating incorporated with the essential oils of Zataria multiflora (ZEO) and Bunium persicum (BEO) on the growth of Pseudomonas artificially inoculated onto salmon fillets over a period of 12 days at 4 °C. Methods: The antibacterial activity of BEO against P. aeruginosa was evaluated using the microdilution method via determining minimum inhibitory concentration and minimum bactericidal concentration. For the food model investigation, three P. aeruginosa strains were inoculated onto trout fillets as culture cocktail to assess their survival over 12 days of storage. Results: The results indicated that ZEO and BEO had stronger inhibitory effect on P. aeruginosa in trout fillets when applied along with gel type nano-emulsion of chitosan solution. The separate use of each of these substances also significantly inhibited the growth of these pathogenic bacteria compared with the control. In addition, the use of chitosan coating without any antimicrobial agent affected the growth of P. aeruginosa. Conclusion: The gel type nano-emulsion of chitosan coating containing ZEO and BEO can be applied on foodstuff, particularly fish and its products, as an antimicrobial agent.