Antimicrobial activity of thyme (Thymus vulgaris) and oregano (Origanum vulgare) essential oils against Listeria monocytogenes in fermented sausages

Drago Nedic,Dragan Vasilev,Mirjana Dimitrijevic,Branislav Vejnovic,Vesna Kalaba,Spomenka Djuric,Bojan Golic,Dragan Kasagic,Tanja Ilic,Nevena Grkovic,Branko Suvajdzic

doi:10.1088/1755-1315/854/1/012064

Abstract

The aim of this study was to investigate antibacterial effects of oregano and thyme essential oils on Listeria monocytogenes in fermented sausages and their effect on the sensory characteristics of these sausages. For testing purposes, sausages contaminated with L. monocytogenes were produced. Changes in the microbiological status of fermented sausages and physicochemical properties were monitored during ripening. Essential oils exhibited antibacterial activity against L. monocytogenes, and in the groups with a high concentration (0.6%) of oregano or thyme essential oils (KLO2 and KLT2), the number of L. monocytogenes was below the detection threshold on day 14 of ripening, with a stronger effect of oregano. In groups with 0.3% essential oil of oregano or thyme added, the number of L. monocytogenes was reduced to below the detection threshold on day 21 of ripening. During the ripening, the aw and pH of all test groups of fermented sausages decreased. Experimental sausages with 0.3% thyme essential oil had acceptable smell and taste, while in other experimental groups, sausage smell and taste were very intense, uncharacteristic and unacceptable.

Highlights

Foodborne listeriosis is one of the most serious and severe foodborne diseases, caused by the bacterium Listeria monocytogenes
Essential oils exhibited antibacterial activity against L. monocytogenes, and in the groups with a high concentration (0.6%) of oregano or thyme essential oils (KLO2 and KLT2), the number of L. monocytogenes was below the detection threshold on day 14 of ripening, with a stronger effect of oregano
In the groups with the addition of a higher concentration (0.6%) of oregano or thyme essential oils (KLO2 and KLT2), L. monocytogenes numbers were below the detection threshold on day 14 of ripening, with a stronger effect of oregano

Summary

Introduction

Foodborne listeriosis is one of the most serious and severe foodborne diseases, caused by the bacterium Listeria monocytogenes This pathogen has been isolated from various ready-to-eat (RTE) food products, including fermented dry and semi-dry sausages [1]. The number of L. monocytogenes decreases during fermentation and drying of sausages because of the set of hurdles created in the manufacturing process (low pH and water activity (aw) and high salt concentration). This microorganism can be isolated from fermented sausages because of its ability to adapt to its environment and because of its presence in raw meat [2]. There is a new trend in the meat industry, where there is no place for artificial preservatives with possible

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