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.