REMOVAL OF LISTERIA SPP. IN A CHEESE FACTORY

A total of 311 samples of 10 mt for liquids and 400-cm(2) for surfaces were analyzed in a cheese plant in Galicia (Spain) within a period of 10 months (Feb. Nov. 1996). Forty-six samples were positive for Liste ria spp., 36 of which corresponded to L. innocua, 8 to L, monocytogene s and 2 to L, welshimeri. Twenty percent of raw milk samples were List eria-positive. Listeria was initially detected on some surfaces of pro duction and ripening rooms, but was never detected after replacing old iron machinery with stainless steel machinery, avoiding the movement of the plant equipment outside the factory building, eliminating woode n boards in the ripening chambers and modifying the disinfection syste m.