Effects of Chitosan Coating Containing Thymol and Eugenol against Listeria Monocytogenes and Escherichia coli O157:H7 Inoculated to Chicken Fillets

The aim of this study was to assess inhibitory effects of thymol and eugenol against Listeria monocytogenes and Escherichia coli O157:H7 as well as assessing ability of chitosan coating containing thymol and eugenol to control Listeria monocytogenes and Escherichia coli O157:H7 inoculated into chicken fillets over a 12-day storage under cold conditions (4 ºC ±1).

Antimicrobial activity of the thymol and eugenol against the bacteria was assessed using microdilution and disk diffusion methods. Chitosan coatings with thymol and eugenol were used to inhibit growth of L. monocytogenes and E. coli O157:H7 cocktails inoculated into chicken fillets during storage for 12 days in refrigerator.

The MIC of thymol against L. monocytogenes and E. coli O157:H7 included 0.3 and 0.6 mg/ml, respectively, and MBC of this compound included 0.6 and 1.25 mg/ml, respectively. The MIC of eugenol against L. monocytogenes and E. coli O157:H7 respectively included 0.6 and1.25 mg/ml and MBC included 1.25 and 2.5 mg/ml, respectively. Assessment of the combined treatments of thymol and eugenol revealed synergistic activities of these compounds against the highlighted bacteria. The average number of bacteria in treated food samples with enriched chitosan coatings of thymol and eugenol and combinations of the two compounds significantly varied (p < 0.05) during 12 days of storage.

Due to the good antimicrobial effects of thymol and eugenol, chitosan coatings enriched with thymol and eugenol and combinations of the two compounds can be used to prevent growth of pathogens on food surfaces, especially chicken meat surfaces, in food industries.