| Summary: | The antimicrobial activity of garlic (<i>Allium sativum</i> L.) and onion (<i>Allium cepa</i> L.) plant active extracts was determined against <i>Listeria monocytogenes</i> in two meat products. Samples of sausages “cacciatore” and cooked ham in vacuum-packaged slices were artificially contaminated, and the presence of <i>Listeria</i> was evaluated during the sausages ripening and throughout the shelf-life of the cooked ham. The test carried out on sausages did not show differences among treated and untreated samples. The antagonistic activity of the plant extracts against the pathogen was probably hidden by the competition from the sausages microbial flora and the pH and the water activity (aw) decrease. On the other hand, the plant extracts determined an initial reduction of about 1.00 log cfu/g of the <i>L. monocytogenes</i> viable count in the cooked ham slices contaminated with 10<sup>3</sup> cfu/g, but the best result was obtained with the contamination of 10<sup>2</sup> cfu/g of <i>L. monocytogenes</i>. In addition to the pathogen’s initial decrease, we observed an extension of the lag phase and a reduction of the <i>Listeria</i> growth rate. Considering that the presence of <i>L. monocytogenes</i> during the slicing phase of the cooked ham does not exceed 10 cfu/g, the use of plant extracts can lead to complete pathogen elimination.
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