Antimicrobial activity of cinnamon oil nanoemulsion against Listeria monocytogenes and Salmonella spp. on melons

Listeria and Salmonella related recalls and outbreaks are of major concern to the melon industry. Cinnamon oil has shown its usefulness in antimicrobial food treatment. However, its applications are limited due to poor solubility of cinnamon oil in water. Utilization of Cinnamon oil nanoemulsion may offer effective antimicrobial treatment to the melon industry. Different formulations of cinnamon oil nanoemulsion were made by ultrasonication using Tween 80 as an emulsifier. The particle size of emulsion was determined by dynamic light scattering. Microbroth dilution assay was performed on Listeria monocytogenes and Salmonella spp. to find out the antimicrobial efficacy of cinnamon oil nanoemulsion. Honeydew and cantaloupe were artificially inoculated with the bacterial strains mentioned above followed by treatment in nanoemulsion (control, 0.1%, 0.25%, and 0.5%) for 1 min. The average diameter of our nanoemulsion was 9.63 ± 0.3 nm. Minimum inhibitory concentration (MIC) of cinnamon oil nanoemulsion for Listeria monocytogenes and Salmonella spp. strains was 0.078% v/v and 0.039% v/v, respectively. Compared to the water control, 0.5% nanoemulsion showed up to 7.7 and 5.5 log reductions in Listeria monocytogenes and Salmonella spp., respectively. The data suggests that cinnamon oil nanoemulsion can be used as an effective natural microbial control agent for melons.