Study the Antibacterial Properties of Echinophora Platyloba and Satureja Bachtiarica Essential Oils and Chitosan Edible Coating on Listeria Monocytogenes in Rainbow Trout Fillet

Present study was done to evaluate the antimicrobial effect of chitosan and Echinophora platyloba and Satureja bachtiarica essential oils on Listeria monocytogenes in Rainbow trout. Essential oil extraction was done from the aerial parts of E. platyloba and S. bachtiarica plants. Minimum inhibitory concentration bacterial concentration of essential oils against bacterium were evaluated by microdilution method. Fish samples were coated using chitosan, E. platyloba (0.062, 0.125 and 0.25 mg/ml) and S. bachtiarica (0.062, 0.125 and 0.25 mg/ml) essential oils. L. monocytogenes (1×103 cfu/g) was inoculated into fish samples and was evaluated during 16 days at refrigerator temperature. The most frequent components detected in S. bachtiarica essential oil were carvacrol (31.25%), thymol (23.50%), o-cymene (13.87%) and Gamma-terpinene (10.65%). The most frequent components detected in E. platyloba essential oil were ocimene (44.15%), alpha-phellandrene (16.80%), gamma-terpinene (8.52%) and beta-myrcene (6.08%). Amount of MIC (0.062 mg/ml) and MBC (0.125 mg/ml) of S. bachtiarica was lower than E. platyloba essential oil. L. monocytogenes was increased in all treatments. The highest number of bacteria in 16th day of maintenance was related to control fish samples and the lowest number was related to chitosan, S. bachtiarica (0.25 mg/ml) and E. platyloba (0.25 mg/ml) essential oils (8.02±0.02 cfu/g) groups. Total volatile nitrogen in control treatment was higher than other samples (P ≤ 0.05). Chitosan and S. bachtiarica (0.25 mg/ml) and E. platyloba (0.25 mg/ml) essential oils had highest sensory scores related to flavor and odor, texture and overall acceptance factors. Use of chitosan, S. bachtiarica and E. platyloba essential oils caused controlling number of L. monocytogenes and total volatile nitrogen and improvement of organoleptic characteristics of samples.