Antifungal activity of lemon balm and sage essential oils on the growth of ochratoxigenic Penicillium verrucosum
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In this study, the chemical compositions of essential oils (EOs) from lemon balm (Melissa officinalis) and sage (Salvia officinalis) were determined using gas chromatography/mass spectrometry (GC/MS) method, indicating that 1,2-propanediol (31.26%) and alpha-thujone (24.92%) were the major components in lemon balm and sage, respectively. In addition, antifungal effects of these EOs against ochratoxigenic Penicillium verrucosum Dierckx (D-99756) isolated from Kashar Cheese were investigated. In order to test their antifungal effects, the EOs dilutions were prepared in methanol at seven different concentrations (500, 250, 125, 62, 31, 15.5 and 7.75 mu l/ml; the values corresponding to 0.5, 0.25, 0.125, 0.062, 0.031, 0.015 and 0.00775% based on agar medium). Their antifungal activities were determined with respect to minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC). The MIC values of lemon balm and sage EOs against P. verrucosum were determined to be the 125 and 62 mu l/ml, respectively; and their MFC values were found to be 250 and 125 mu l/ml, respectively, indicating that sage exhibited two fold fungistatic and fungicidal effect against ochratoxigenic P. verrucosum than did lemon balm. The results of this study suggest that lemon balm and sage EOs can be considered as natural antifungal agents that can be used to inactivate ochratoxigenic P. verrucosum with respect to food safety applications.