QUANTIFICATION OF PSYCHROTROPHIC AND PROTEOLYTIC MICROORGANISMS IN “MINAS FRESCAL” CHEESE

Psychrotrophic microorganisms have ability to growth at temperature below 7 °C, what characterizes their group one the most important degradative agents of raw refrigerated milk and derivatives. Some of their microorganisms produce proteolytic enzyme, also called protease, which are responsible to protein degradation which cause technological and economic problems to the dairy industry. That heat-resistant enzyme degrade milk components, conferring high acidity to the medium, reducing cheese shelf life and causing sensorial changes undesirable like taste, flavor and aroma in dairy products. By quantification of psychrotrophic and proteolytic microorganisms, the present work aimed to evaluate the quality of “Minas Frescal” cheese produced at north region of Minas Gerais. For that were collected cheese samples from municipal market of Salinas-MG, and after, transported at the Microbiology Laboratory of the Federal Institute of North of Minas Gerais, was submitted to analyzed microbiological realized at four times, 0, 2, 5 e 7 days, representing t1, t2, t3 e t4. The psychrotrophic and proteolytic microorganisms counting proceeded as standard established by the Ministry of Agriculture, IN 62 out of August 23th, 2003 using a Plate Count Agar (PCA) additional 2% milk, were enumerated after 10 days of incubation at 7 °C. The presence of proteolytic bacteria was associated of formation a clear halo surroundings the colony, that conditional prove consumption of milk proteins presents in medium. On cheese stored at 7°C the psychrotrophic initial counts were 4,36x107 colony forming unit per gram (CFU/g), but on prolonged storage periods of 2, 3 and 4 days the detected respectively value range for 4,09x107 CFU/g; 9,73x107 CFU/g; 9,50x107 CFU/g. Ours results coincide with those described in the literature, that affirms about the positive growth of the microbial group, the psychrotrophic and proteolytic microorganisms, was count from 5,6 x105 CFU/g to 8,58x106 CFU/g across 7 days on storage, confirming the growth the psychrotrophic and proteolytic microorganisms of dairy products under refrigerated storage. Concluding was observed the high counts of psychrotrophic on “Minas Frescal” cheese, what means the existence of failures during the production process, causing damages to quality at final products and reducing shelf life of dairy products.