Impact of Essential Oils Composition and Exposure Methods on Fungal Growth and Morphology: Insights for Postharvest Management

Abstract

Postharvest fungal diseases caused by Colletotrichum, Rhizopus, and Penicillium are major concerns, driving the search for sustainable antimicrobial alternatives to enhance food shelf life. This study examines the chemical composition of essential oils (EO) from Origanum vulgare, Syzygium aromaticum, Cymbopogon citratus, Cymbopogon martinii, Mentha piperita, and Mentha spicata, evaluating their in vitro effectiveness against Colletotrichum sp., Rhizopus stolonifer, and Penicillium expansum. Different EO concentrations were tested via volatile exposure and direct contact to determine the minimum inhibitory concentration (MIC) for each fungus. The results indicate that there is no universal strategy for prevention and control, as the effectiveness of EO depends directly on the fungal species. Colletotrichum sp. and R. stolonifer were more susceptible to volatiles from O. vulgare (200 μL/L_air) and M. piperita (180 μL/L_air), respectively, whereas P. expansum was more sensitive to direct contact with O. vulgare (250 μL/L_medium). Scanning electron microscopy (SEM) revealed that O. vulgare, rich in phenolic terpenes, and C. citratus, rich in aldehydic monoterpenes, induced hyphal breakage and twisting at varying intensities in these three common postharvest fungi. The results highlight the potential of EO via volatile exposure and direct contact as a promising alternative for postharvest fungal control.