Investigating Chemical Composition of Zataria multiflora Boiss and Ziziphora clinopodioides Essential Oils in Chitosan Nanoemulsion Coating on Growth of Aeromonas Hydrophila Inoculated in Salmon Fillets

Background and Objectives: Foodborne diseases have been the most important human health risks and the present study was carried out to investigate how to decrease these risks. The objectives of this paper were to investigate chemical compositions of Zataria multiflora Boiss and Ziziphora clinopodioides essential oils in chitosan nanoemulsion coating on growth of Aeromonas hydrophila inoculated in salmon fillets within 12 days of storage at cold temperatures (4 °C ±1) and antibacterial activity of the essential oils (emulsion and nanoemulsion) against highlighted bacteria using minimum inhibitory concentration and minimum bactericidal concentration methods.  Materials & Methods: Chemical composition of the essential oil was assessed using gas chromatography and the treatments were divided into six major groups of no cover (control), chitosan, chitosan nanoemulsion, chitosan nanoemulsion containing 0.5% Zataria multiflora Boiss, chitosan nanoemulsion containing 0.5% Ziziphora clinopodioides and chitosan nanoemulsion containing Zataria multiflora Boiss and Ziziphora clinopodioides. Samples were stored in refrigerator for bacterial counting on Days 0, 1, 2, 4, 8 and 12. Results: Carvacrol (44.36%), thymol (30.14%) and γ-terpinene (8.31%) were identified as the most important compounds in chemical composition of Zataria multiflora Boiss essential oil. The most important compound in chemical composition of Ziziphora clinopodioides essential oil was pulegone (48.19%). The mean logarithm of the bacterial number within 12 days showed significant differences between the groups (p < 0.05). The present study showed that the highest inhibitory effects on the bacteria were in treated samples with chitosan nanoemulsion containing Zataria multiflora Boiss and Ziziphora clinopodioides essential oils, compared to control group. Conclusion: Results of this study have shown that nanoemulsion of chitosan edible coating is effectively capable of inhibiting growth of Aeromonas hydrophila in salmon fillets at cold temperatures. Furthermore, the nanoemultion can be used in food industries.