Determination of Antifungal Effects of Plant Essential Oils against Some Fungal Disease Agents Causing Internal Rot of Dried Pepper Fruits

Abstract

Fungal disease agents that cause fruit internal rot in agricultural products before and after harvest cause serious quality and yield losses, while the mycotoxins they produce in foods pose a health risk for consumers. Alternaria alternata and Aspergillus niger were determined as the most common fungal disease agents as a result of the isolations made from dried pepper fruits showing signs of internal rot. In this study, antifungal effects of different vapour doses of essential oils in the vapor phase of different thyme species (Thymus vulgaris L., Tymbra spicata L. and Origanum syriacum L.), fennel (Foeniculum vulgare Mill.), laurel (Laurus nobilis L.) and eucalyptus (Eucalyptus camaldulensis Dehnh) were investigated against postharvest pathogens A. alternata and A. niger in pepper in vitro conditions. The highest antifungal activities (100% inhibition) against all tested fungal isolates were displayed by essential oils of Thymbra spicata (2.0-4.0 µl petri-1), Origanum syriacum (4.0 µl petri-1) and Thymus vulgaris (4.0-6.0 µl petri-1). Eucalyptus camaldulensis (16.0-40.0 petri-1) exhibited the lowest antifungal activity against tested fungal isolates. In addition, the antifungal properties of essential oils and their EC50 values were also determined. Plant essential oils showed antifungal effects against the tested fungal isolates in a dose-dependent manner. The obtained results showed that plant essential oils might be applied as biofumigant in dried agricultural products.