On the microbiology of Serra da Estrela cheese: geographical and chronological considerations

Abstract

Serra da Estrela cheeses, produced following artisanal practices from raw ewe's milk in two consecutive years in five selected dairies, were sampled throughout a 60-day ripening period. The viable numbers of the major microbial groups (Enterobacteriaceae, staphylococci and yeasts, as well as such lactic acid bacteria as lactobacilli, lactococci and enterococci) were determined and statistical significance of the results was assessed. Significant differences in the viable counts of lactococci, lactobacilli, enterococci, Enterobacteriaceae and staphylococci were found for the various geographical locations, whereas the year of manufacture played a significant role only upon the viable numbers of yeasts and staphylococci. These data back up the claim that those microbial families usually implicated with health hazards are prone to a wide variability, which reflects the intrinsic heterogeneity associated with production and handling of raw milk in traditional cheesemaking.