Antibacterial activity of cinnamaldehyde and clove oil: effect on selected foodborne pathogens in model food systems and watermelon juice.

Natural additives for the control of microbial growth are in demand because consumers prefer them over synthetic ones. In the present investigation, the antibacterial activity of two natural preservatives, cinnamaldeyde and clove oil alone or in combinations was studied, and their potential as food preservative in model food systems and watermelon juice was evaluated. The cinnamaldehyde and clove essential oil showed minimum inhibitory concentration (MIC) at or below 5000 mg/l, and fractional inhibitory studies using both the oils showed synergistic effect. In artificially inoculated barley model food system and cabbage model food system, 2 MIC of oils was able to reduce the growth of the tested bacteria (more than 5 log) during 4 weeks storage at 37 °C, and similar reduction was also observed when combinations of oils were used at one eighth of MIC against Bacillus cereus and Yersinia enterocolitica, and one fourth of MIC against Staphylococcus aureus and Escherichia coli. Natural contaminants of watermelon juice were also reduced by the combination of one fourth of MIC of the oils, which was more effective than individual 2 MICs. These findings may be useful for food applications, but their effect on sensory quality of various foods need to be studied.