Determination of Antifungal Activities of Some Plant Fixed and Essential Oils Against Three Penicillium Species

Some members of the Penicillium genus are storage molds that cause spoilage of agricultural products during storage and distribution. It is crucial to control Penicillium digitatum and Penicillium italicum, which are green-blue molds that cause spoilage, especially of citrus fruits, during storage. While synthetic chemical preservatives can be used for this purpose, the increasing concern over synthetic chemicals and the rising consumer interest in natural products make it important to explore alternative natural options for protecting products during storage. Therefore, in this study, the antifungal activities of 135 plant fixed and essential oils against Penicillium digitatum (CECT 2954), Penicillium italicum (CECT 2294), and Penicillium notatum (NRRL 807) were evaluated using agar well diffusion, microdilution, and radial growth inhibition methods. Nine oils showed antifungal activity against the tested Penicillium species using the agar well diffusion method. Thyme oil (77) demonstrated both MIC and MFC values of 1 μL/mL and exhibited fungicidal activity. Lemon oil (84) and peppermint oil (93, 94) were found to have MIC values of 1 μL/mL and MFC values of 20 μL/mL, respectively, and exhibited fungistatic properties. When the effect of thyme oil on the radial growth of Penicillium species was examined over 21 days, it was observed that 100% inhibition was achieved, while the effects of lemon and peppermint oils decreased over time. In conclusion, plant fixed, and essential oils can act as natural antifungal agents. However, their effectiveness may decrease over time during storage due to the volatility of their components. As a result, creating various controlled release or delivery systems is essential.