Evolution of Listeria monocytogenes populations during the ripening of naturally contaminated raw ewe’s milk cheese

The aim of this work was to study, in loco, the evolution of Listeria monocytogenes populations, during ripening (7, 42, 60 and 120 days) of naturally contaminated raw ewe’s milk cheese. Two batches of cheese consisting of 20 or 16 cheeses were obtained from two farmstead cheesemakers, respectively. A significant increase in numbers of L. monocytogenes was observed for both batches, from 7 to 42 days of ripening. These results suggest that this type of cheese has potential to support the survival of L. monocytogenes, while stressing the importance of cheese contamination in the dairies by resident strains.