Essential oils on the control of postharvest diseases of papaya

Papaya is susceptible to fungal deterioration and the use of essential oils (EOs) emerges as a promising alternative to fungicides, which causes environmental and human health problems. To evaluate the antifungal activity of essential oils and their major constituents in controlling papaya pathogens, the following in vitro assessments were conducted: I) screening of seven EOs regarding the antifungal activity; II) determination of the minimum inhibitory concentration (MIC) of the most promising EOs; III) analysis of chemical composition of the most effective oils; and IV) evaluation of the antifungal potential of the major constituents both individually or in combination. The results showed that the EOs of cinnamon bark, oregano, clove basil, and rosemary pepper exhibited high antifungal activity against all studied fungi, with MIC values from 0.50 to 2.00 μL mL-1. The major constituents found in oregano EO were carvacrol, ρ-cymene, and thymol; in cinnamon bark EO, cinnamaldehyde, o-methoxy, and cinnamyl; in rosemary pepper EO, thymol, ρ-cymene, and caryophyllene; and in clove basil EO, eugenol, ρ-cymene, and caryophyllene. Regarding the antifungal activity of the EO constituents, the mixture of the three major demonstrated greater efficiency against the studied fungi. Using constituents represents an alternative for controlling postharvest diseases in papaya.