Changes in the microflora of Serra cheese: evolution throughout ripening time, lactation period and axial location

Changes in the microflora and physicochemical characteristics in Serra da Estrela cheese were examined using a three-way factorial design over a 35 day ripening period, throughout the lactation period, and for several slices taken normal to the cheese axis. Lactic acid bacteria were the major components of the microflora during ripening throughout the lactation period, but no statistically significant differences were detected between the surface and the interior of the cheese. Both enterobacteriaceae and staphylococci in the curd were at maximum numbers during the first week and were still at significant numbers towards the end of the maturation period. The numbers of staphylococci were statistically different between slices and at different times within the lactation period, whereas the numbers of enterobacteriaceae showed statistically significant variations only throughout the lactation period. Ripening time, lactation period and axial location significantly affected the number of yeasts. All factors studied had statistically significant effects on pH, salt and moisture content; the hypotheses that ripening time, lactation period, and axial location had effects on salt and moisture contents were accepted, in this order, at increasingly lower levels of significance; the hypotheses that ripening time, axial location, and lactation period had effects on pH were accepted, in this order, at increasingly lower levels of significance.