MICROBIOLOGICAL STUDY OF ARZÚA CHEESE (NW SPAIN) THROUGHOUT CHEESEMAKING AND RIPENING

Changes during production and ripening in the microbial flora of 11 batches of Arzúa, a soft cheese made from raw cow's milk, were investigated. The following microbial groups were counted on the surface and interior of the cheese: total viable count (TVC), lactic acid bacteria (LAB), halotolerant flora, enterococci, proteolytic enterococci, staphylococci, 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 remained practically constant throughout ripening, at 6–8 and 5–7 log units, respectively. Maximum Enterobacteriaceae and faecal coliform counts exceeded 7 and 6 log units, respectively. Brucella spp. were not detected in any of the milk samples. Listeria spp. were detected in four batches, and Listeria monocytogenes in two.