Purpose: To evaluate antimicrobial effects of cinnamon oil against Salmonella in a media setting and on almonds.
Methods: Antimicrobial effects of cinnamon oil against Salmonella Enteritidis PT30 and Salmonella Tennessee K4643 were evaluated by disk diffusion, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and death curve. Its inhibitory effects against Salmonella on almond or paper disks, a carrier to mimic low-moisture environment, were further examined during storage at room temperature.
Results: The disks with 20µl of 4% (v/v) cinnamon oil resulted in inhibition zones of 1.93 and 1.63 cm for Salmonella Enteritidis PT30 and Salmonella Tennessee K4643, respectively. MIC and MBC of cinnamon oil against both strains were 0.05% (v/v) and 0.1% (v/v), respectively. Cinnamon oil at 1.5× MBC reduced both strains in LB broth under the detection level (more than a six-log reduction) within one hour. Salmonella established either on almond or paper disk was very stable during seven to nine weeks of storage at room temperature, there was ~ one-log reduction over storage. 0.4% Cinnamon oil treatment initially caused ~ one and 2.6-log reduction of Salmonella on almond and paper disk, respectively compared to PBS control. Additionally, cinnamon oil treatment resulted in ~ two-log reduction of Salmonella on almond during nine-week of storage, while, on paper disk, reduced Salmonella below the detection level after four weeks of storage.
Significance: Cinnamon oil demonstrates antimicrobial efficacy against Salmonella, and has the potential to be used as a promising natural compound to control Salmonella on almonds. Food matrix or almond skin components increased Salmonella resistance against cinnamon oil.