MICROBIOLOGICAL STUDY OF ARZUA CHEESE (NW SPAIN) THROUGHOUT CHEESE-MAKING AND RIPENING

Changes during production and ripening in the microbial flora of 11 ba tches of Arzua, a soft cheese made from raw cow's milk, were investiga ted. The following microbial groups were counted on the surface and in terior of the cheese: total viable count (TVC), lactic acid bacteria ( LAB), halotolerant flora, enterococci, proteolytic enterococci, staphy lococci, Staphylococcus aureus, Enterobacteriaceae, faecal coliforms, molds, yeasts, Listeria spp. and (in milk) Brucella spp. pH and water activity were also determined. TVC and LAB were, generally, more than 9 log (cfu/g). Enterococci counts increased gradually, reaching values in excess of 6 log units. Halotolerant flora and staphylococci remain ed practically constant throughout ripening, at 6-8 and 5-7 log units, respectively. Maximum Enterobacteriaceae and faecal coliform counts e xceeded 7 and 6 log units, respectively. Brucella spp. were not detect ed in any of the milk samples. Listeria spp. were detected in four bat ches, and Listeria monocytogenes in two.