Combined antifungal effects of the vapor phases of Zataria multiflora and Cinnamomum zeylanicum essential oils against Aspergillus flavus and Penicillium citrinum in vitro and cheese

The objective of this study was to evaluate the antifungal effects of Zataria multiflora (ZEO) and Cinnamomum zeylanicum (CEO) essential oils in the vapor phase against Aspergillus flavus and Penicillium citrinum in vitro and cheese. The antifungal activities of the vapors of ZEO and CEO were assessed by determining the minimum inhibitory concentration (MIC), fractional inhibitory concentration (FIC) index, and inhibition zone diameters. Thymol (51.10%) and cinnamaldehyde (77.82%) were the main constituents of ZEO and CEO, respectively. The MIC values of the vapors of ZEO and CEO against A. flavus were 25 and 12.5 μL/L and against P. citrinum were 800 and 400 μL/L, respectively. The in vitro results showed that the combination of the vapor phases of ZEO and CEO could synergistically inhibit the growth of A. flavus (FIC index = 0.75). In the cheese, the growth of P. citrinum was entirely inhibited by the combination of ZEO and CEO vapors, even at very low concentrations (1/16 MIC). In conclusion, the vapor phases of ZEO and CEO showed the potential to be applied as effective natural antifungals and alternatives to synthetic preservatives in cheese.