IMPROVEMENT OF QUALITY OF RAS CHEESE MADE FROM PASTEURIZED MILK USING A SPECIAL SLURRY FROM EWE'S MILK

The present study was carried out as an at-tempt to improve the quality of Ras cheese made from pasteurized cow's milk using ewe's milk slurry to which proteases and lipases were added. The slurry was incubated at 30ºC for one week, and then added either to the cheese milk prior to coag-ulation or directly to the cheese curd before press-ing. Cheeses were analysed for chemical, microbi-ological and organoleptic properties at 0, 15, 30, 60 and 90 d of ripening. Generally, the addition of slurry affected at least four parameters of interest for the flavour development. Cheese flavour devel-opment was accelerated, the proteolysis was en-hanced and casein breakdown was stimulated. Addition of slurry increased the levels of the total volatile fatty acids at each period of ripening, par-ticularly with addition of slurry to cheese curd. Ad-dition of slurry affected the microbiological quality of cheeses. Proteolytic and lipolytic bacterial counts increased throughout ripening, while yeast and moulds were no longer detectable in slurry added cheese after 30 d of ripening. Sensory eval-uation showed that the Ras cheeses made with the slurry received higher scores for flavor and body and texture than the control cheese over 90 d of ripening. These results suggested that the addition of ewe's milk slurry was necessary for develop-ment of sensory characteristics of the cheeses.