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Abstract
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Listeria monocytogenes has gained increasing attention as a pathogen of public health importance owing to large numbers of foodborne outbreaks of listeriosis. In this study we have evaluated the effects of Salvia sclarea and Ocimum basilicum essential oils (EOs) on the growth of Listeria monocytogenes PTCC 1298 in white feta cheese. MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) obtained for salvia against L.monocytogenes were 0.015% and 0.02%, and for basil were 0.05% and 0.06%, respectively. Significant differences were also observed in the activity against Listeria between the three concentrations of basil EO and the control, but the maximum difference was recorded after 7 days. Increasing the concentration of basil EO to 1% enhanced its inhibitory effect against L. monocytogenes. On the last day of storage the difference between samples treated with 1% basil EO and the control was more than 3 log cfu g-1. The mean counts of L. monocytogenes in cheese samples treated with salvia and basil EOs were 1.66 and 5.91 log cfu g-1, respectively, after 21 days. A difference of 4.25 log cfu g-1 between the two EOs showed that salvia EO had a notably stronger activity against Listeria. At 1%, salvia reduced bacterial growth up to 6 log cfu g-1 in the cheese throughout the storage period. By comparison, basil showed weaker antimicrobial effect in cheese.
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