Pasteur Institute of Iran

Introduction: In this study, the chemical composition and antimicrobial activity of essential oil of Ziziphora clinopodiodes and its potential application as a natural preservative in reducing the indigenous microbial population of hamburger were investigated. Method: Essential oil of Ziziphora clinopodiodes cultivated in Iran was obtained by Hydro-distillation method (HDM). Chemical composition of the oil was determined by gas chromatography/mass spectrometry (GC-MS) analysis. Antimicrobial activity of the essential oil was checked against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Salmonella typhi, Listeria monocytogenes, Pseudomonas aeruginosa, by using Agar dilution method (ADM). Minimum Inhibitory Concentration (MIC) values of each active oil concentration were determined and its potential application as a natural preservative in reducing the indigenous microbial population of hamburger was investigated. Results: The major components were carvacrol (54.31%), thymol (12.51%), octadecane (9.51%) and pulegone (4.88%). The results showed a significant activity against the tested strains (gram-positive and gram-negative bacteria). Addition of essential oil in concentration higher than MIC values reduced the microbial population of hamburgers stored at 25°C, 4°C and -12°C. In samples refrigerated at 4°C, differences between the controls and samples treated with essential oil at MIC values (0.20 and 0.4 mg/ml)  were  not  significant  during the first 24 h (p> 0.05), but higher concentration of essential oil resulted in about 2 to 3 log reduction in total microorganisms. Conclusion: This study showed that the Ziziphora clinopodiodes essential oil can be added to the ingredients of foods as the natural antibacterial agent.