Abstract:

Abstract In this study, effect of storage on chemical composition, antibacterial and antifungal activities of Mentha piperita L. essential oil was investigated. Essential oils of oven-dried plant samples were obtained by hydro-distillation, analyzed by gas chromatography/mass spectrometry and stored in a refrigerator at 4 ⁰C and in a freezer at -20 ⁰C for one, three and six months. Antibacterial and antifungal activity of the essential oils against some gram-positive (Bacillus cereus, Staphylococcus aureus, Bacillus subtilis, Micrococcus luteus), gram-negative (Escherichia coli, Proteus vulgaris, Klebsiella pneumoniae, Yersinia enterocolitica) bacterial strains and fungi (Candida albicans, Aspergillus niger) were evaluated by agar well diffusion method. Storage period antibacterial and antifungal activities of the essential oils increased. In general, essential oils stored at -20 ⁰C produced more antimicrobial activity than those stored at +4 ⁰C. The most affected microorganisms by essential oils were Staphylococcus aureus, Proteus vulgaris and Aspergillus niger. The results of the present study revealed that antibacterial and antifungal properties of Mentha piperita L. essential oil could be preserved and even improved when stored in proper temperature and period.

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