Comparative study on the antibacterial properties of nanoemulsion of Zataria multiflora essential oil fortified with cinnamaldehyde against common foodborne pathogens

Background: Nowadays, the application of several and natural preservatives in small quantity is a more preferred approach. In this regard, one of the effective methods is the formation of nanoemulsion of essential oils. Objective: The objective of this study was to compare the in vitro antibacterial activities of cinnamaldehyde (CIN) and Zataria multiflora essential oil in conventional (ZEO), nanoemulsion (NZEO) and fortified nanoemulsion (NZEOC) forms against common foodborne pathogens. Methods: Firstly, the Zataria multiflora essential oil was analyzed by GC-MS. The nanoemulsion of Z. multiflora essential oil was then prepared alone and fortified with cinnamaldehyde. Finally, their antimicrobial activity against Listeria monocytogenes, Staphylococcus aureus, Salmonella enteritidis and Escherichia coli was evaluated. Results: Based on the results, carvacrol (36.62%) was found to be the most important compound of essential oil. In disc diffusion and micro-dilution methods, the addition of CIN to ZEO during nanoemulsion formation (NZEOC) showed more antibacterial activity when compared to the individual addition of NZEO and CIN (NZEO+CIN). However, according to the vapor phase diffusion method, nano-treatments exhibited less inhibitory effects than the other treatments. Conclusion: It can be concluded that the fortification of essential oils with their derived pure compounds during nanoemulsion formation, can be used as a suitable alternative to chemical antibacterial compounds in the food industry.