Purpose: This study investigated the antibacterial activity of cinnamaldehyde emulsions (3-fenil 2-propenal) extracted from cinnamon bark oil against three important foodborne pathogens: Salmonella enterica, Staphylococcus aureus and Listeria monocytogenes.
Methods: Two nonionic emulsifiers (Tween 85 and Span 20) were used to stabilize the essential oil in water. Antimicrobial activity of emulsions was tested by well diffusion agar test. Minimum Inhibitory Concentration (MIC) was determined for cinnamaldehyde emulsified with Tween 85 and Span 20. The reduction of inoculated S. enterica, L. monocytogenes, and S. aureus on tomatoes with cinnamic aldehyde emulsion was evaluated at low density of pathogens on tomato surface (4 log CFU/tomato). Differences among treatments were determined by Duncan test at significant level of 0.05.
Results: Inhibition zone diameters from 16-36 mm were obtained at concentrations of 0.5 to 1.5% of cynnamaldehyde emulsions prepared with tween 85, and from 14 - 49 mm for emulsions prepared with span 20. For emulsions prepared with span 20, the MIC were below 0.25% for pathogen suspensions at 4 log CFU/ml and up to 0.5% for pathogen suspensions at 6 log CFU/ml. Reductions between 95% and 98%, equivalent to 2 log CFU of the inoculum were obtained on inoculated tomatoes treated with 0.5% cinnamaldehyde emulsion by immersion for five min, which were significantly different than the results showed on inoculated tomatoes immersed in water (P < 0.05).
Significance: More research is necessary in order to determinate the feasibility of the industrial use of these emulsions.