Microbial changes during the ripening period of the cheese of Evora

The cheese manufactured in Evora (South East Portugal) commercially designated Evora cheese, is made from raw ewe's milk following local and traditional technology. Manufacture of Evora cheese begins in December and continues until May-June. The ripening period is about 30 to 60 days. The local importance of this type of cheese as well as the need to understand the microbiological aspects involved during the maturation process, prompted our studies on this subject. Samples were taken every two weeks starting mid January until mid May, involving ten manufacturing dates. Milk, curd and cheeses 3, 7, 30, 45 and 60 days old were analysed for the following: i) number of total viable bacteria; ii) number of lactic acid bacteria; iii) number of coliform bacteria; iv) number of enterobacteria; v) number of enterococci and v) number of yeasts. Results obtained show a variation on the number of those groups of micro-organisms present in samples taken in winter when compared to those taken in spring. Lactic acid bacteria predominated over the other groups. Counts of this group were higher in the end of the ripening period (45 or 60 days) for cheeses produced in winter whereas in those produced in spring, the highest counts occurred at 3 or 7 days of ripening. The counts of enterobacteria and coliforms decreased towards the end of the ripening period being the lowest values obtained from cheeses made in spring. These data tend to indicate a relationship between the microbial Variability observed in the tested periods of cheese manufacture (winter versus spring) and the sanitary conditions and other characteristics of the Evora cheese.