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

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.