Assessing the Listeria monocytogenes transference during mechanical slicing of mozzarella cheese

Listeriosis is a foodborne disease caused by Listeria monocytogenes (LM) and has been linked to the consumption of sliced mozzarella cheese. This study aimed to assess the LM transference during mechanical slicing of mozzarella cheese and its growth during refrigerated storage. Mozzarella cheese was contaminated with LM and 100 slices containing approximately 5 log CFU/slice were produced. Next, 100 slices of non-contaminated cheese were sliced using a contaminated blade (3.67log CFU/10 cm²). LM was quantified on the blade and slices right after slicing and after storage at 10 °C for 10 and 15 days. Results demonstrated that increasing counts of LM were transferred to the blade, comparing the first and the fifth slices (2.71 and 3.22log CFU/10 cm², respectively, p ≤ 0.05), however, transference stabilized after the 50th slice (3.75 CFU/10 cm²). The blade transferred 1.69-2.66 log CFU/g of LM to different slices. At the end of the storage at 10 °C by 10 and 15 days, LM counts increased to 1.51 and 1.69 log CFU/g, respectively, indicating that LM population can increase if the cheese is stored for a long time.