Purpose: The purpose of this study was to test the antimicrobial efficacy of cinnamon oil nanoemulsion on melons against major foodborne pathogens such as Listeria monocytogenes and Salmonella enterica.
Methods: Different formulations of cinnamon oil nanoemulsion was made by ultrasonication using Tween 80 as emulsifier. Nanoemulsion exhibiting the smallest oil droplets was applied. Oil droplets were characterized for particle size by dynamic light scattering. Microbroth dilution assay was performed on three strains each of L. monocytogenes and S. enterica to find out the antimicrobial efficacy of cinnamon oil nanoemulsion. Honeydew melons were artificially inoculated with the above mentioned strains followed by treatment in nanoemulsions (control, 0.1%, and 0.25%) for one minute. Samples were dried and enumerated after one hour of treatment on selective media (PALCAM and XLD agar).
Results: The average diameter of nanoemulsions was 19.6 nm. Minimum inhibitory concentration (MIC) of cinnamon oil nanoemulsion for both Listeria and Salmonella strains was 0.078% v/v and 0.039% v/v, respectively. The minimum bactericidal concentration was 0.078% v/v for both. Compared to the water control, melon showed one-log reduction in L. monocytogenes and two-log reduction in S. enterica, respectively. 0.5% v/v of nanoemulsions might yield better log reduction in future trials.
Significance: The data suggest that cinnamon oil nanoemulsion can be used as an effective natural microbial control agent for honeydew melons.