Effect of the essential oils of Thymus vulgaris, Cinnamomum zeylanicum and Mentha piperita on fungal growth and morphology

This study aimed to evaluate the antifungal activity of essential oils of Thymus vulgaris L., Cinnamomum zeylanicum B. and Mentha piperita L. on some saprophytic fungi. Essential oils were extracted by hydro-distillation, and chemical composition was analysed by gas chromatography coupled with mass spectrometry (GC-MS). T. vulgaris had as major components, Thymol (35.12%), p-cymene (25.36%) and γ–terpinene (12.48%). E-B-Caryophyllane (21.82%), E-Cinnamaldehyde (13.03%) and eugenol (12.15%) were primary in C. zeylanicum. Menthol (33.59%), menthone (18.47%) and α-pinene (8.21%) were primary in M. piperita. Applying the micro-atmospheric method, essential oils were tested against Rhizopus oryzae Went & Prins, Rhizopus stolonifer Ehrenb, Aspergillus tamarii Taka, Aspergillus parasiticus Speare, Aspergillus flavus Link and Talaromyces purpureogenus purpureogenum. The minimum inhibitory concentrations were 3 to 8, 5 to 16 and 13 to 23 μL/75mL air space for T. vulgaris, C. zeylanicum and M. piperita, respectively. Means of percentage inhibition were compared through one-way ANOVA by the Tukey test. Scanning electron microscopy revealed fungal cell wall deformation after exposure to essential oil vapour. These essential oils can be exploited as alternatives to synthetic food preservatives. Key words: Essential oil, Aspergillus, Rhizopus, Talaromyces, fungal morphology, food preservation.