INFLUENCE OF ESSENTIAL OILS ON THE VIABILITY OF LISTERIA MONOCYTOGENES

Document Type : Research article

Authors

1 Department of Food Hygiene, Animal Health Research Institute, Agriculture Research Center, Egypt

2 Department of Food Hygiene, Faculty of Veterinary Medicine, Assiut University, Egypt.

3 Animal Health Research Institute, Food Hygiene, Assiut Regional Lab., Egypt.

Abstract

The present investigation was applied to study the influence of cinnamon (C), rosemary (R) and thyme (T) essential oils (EOs) on the viability of Listeria monocytogenes, in which, a total of 225 cheese samples (Tallaga, Bramily and Ras cheese, 75 each) were collected from different dairy markets and shops in Assiut city, Egypt for the isolation of L. monocytogenes. The isolates were identified and examined for 16S rRNA as positive for L. monocytogenes. The obtained results showed that Listeria spp. could be detected in 66.2% of the examined samples, while L. monocytogenes was in 17.6%. After that, the minimum inhibitory concentration (MIC) of the prepared cinnamon EO (CEO), rosemary EO (REO) and thyme EO (TEO) was detected against the isolated L. monocytogenes. Samples of Tallaga cheese were manufactured using MIC of the 3 prepared EOs separately, and the influence of EOs was done by agar well diffusion method and showed the MIC as 1.56% for CEO, 3.125% for REO and TEO. In conclusion, the CEO was the most effective against L. monocytogenes after Tallaga cheese manufacture although the unpleasant sensory quality of the manufactured cheese with the 3 oils, in which, the count of L. monocytogenes was 6.3 log10 at 0 h and then was 2.7 log10 after 1st week.

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