This master's thesis aimed to determine when the number of coagulase-positive staphylococci (CPS) and E. coli is at its highest during the process of making fresh and ripened cheeses. That would help to clarify the optimal time for sampling fresh and ripened cheeses for the enumeration of CPS and E. coli as it is suggested in Commission Regulation (EC) No 2073/2005. We also analyzed the occurrence of these species of bacteria in cheeses on the Slovenian market. We used the horizontal methods for the enumeration of CPS (ISO 6888-2) and E. coli (ISO 16649-2) by counting the colonies obtained on a solid medium. We sampled the cheeses upon their acceptance and during their storage or ripening, adjusting the frequency of sampling according to the results. Results revealed that the number of CPS and E. coli in ripened cheeses made from pasteurized milk and fresh cheeses is the highest right after their production and is decreasing during their storage or ripening. In the case of ripened cheeses made from raw milk, the number of CPS rises during the first days of ripening and decreases later on. So, the sampling of ripened cheeses made from pasteurized milk and fresh cheeses for the enumeration of CPS and E. coli should be carried out right after their production and before ripening, the sampling of ripened cheeses made from raw milk for the enumeration of E. coli should be done 3 days into the ripening and for the enumeration of CPS 4 days into the ripening. We also found out that the cheeses on the Slovenian market only partly meet the criteria for microbiological safety regarding CPS (83,3 %) and E. coli (73,3 %).
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