Anti-Listeria activity of citrus essential oils in a fresh ovine cheese

The aim of this study was to evaluate the anti-Listeria activity of essential oils (EOs) extracted from the peel of lemons, oranges and tangerines in a fresh cheese produced with pasteurized ewe’s milk. Four cheesemaking trials were performed at the pilot plant scale level, including one control production without the addition of EOs and three experimental productions obtained by the addition of 200 μL/L of each EOs to milk. Before the addition of EOs, the milk of all trials was inoculated with 107 CFU/mL of the starter cultures (Lactococcus lactis NT1 and NT5) and 104 CFU/mL of pathogenic bacteria (Listeria monocytogenes ATCC19114). Plate counts confirmed the dominance of the starter cultures and a significantly reduction of L. monocytogenes in experimental cheeses. This work indicated that the addition of citrus EOs to milk represents an effective natural alternative to synthetic substances to enhance the microbial safety of this fresh cheese.