Assessment of microbiological, physico-chemical and enzymatic parameters of pasteurized Milk and type B, produced in Paraná, Brazil

Abstract

In 2006, Paraná State produced 2,7 billion liters of milk. Despite the great production, in general, milk is still produced under poor hygienic and sanitary conditions, which leads to an elevated number of microorganisms that reduce the quality and represent risk to consumer’s health, particularly when consumed without heat treatments. As a result, quality was the focus in the PNMQL (National Plan for the Improvement of Milk Quality), that created the Normative Instruction 51(IN 51), which determines important standards to improve milk quality. Therefore this work aimed to evaluate microbiological and physical-chemical quality of pasteurized milk in different municipal districts of Parana State between 2006 and 2008, years that follow IN 51 implementation. Milk samples from 39 different dairy industries were analyzed, adding up to 192 samples. From those, 70 milk samples were classified as type B pasteurized and the 122 samples was classified as pasteurized milk. Within the 192 analyzed samples of milk 58 (47,54%), 17 (13,93%) and 29 (23,77%) presented results above legal limits for coliforms at 30°C, coliforms at 45°C and mesophilic aerobes, respectively. While to type B milk samples results above legal limits found were 23 (18,85%), 4 (3,28%) and 6 (8,57%) for coliforms at 30°C, coliforms at 45°C and mesophilic aerobes. In regard to the analyses of dornic acidity, fat percentage, densidade, dry fat free extrat and crioscopy the results outside legal standards were 33 (17,19%), 14 (7,29%), 7 (3,65%), 35 (18,21%) and 30(15,63%), respectively.It can be concluded from this work that type B milk presented better microbiological quality than pasteurized milk. The most frequent microbiological alterations were observed for the Coliforms 30ºC analysis of pasteurized milk, for type B milk the higher counts were obtained for mesophilic aerobes. There was an improvement in quality in the two types of milk analyzed over the years that followed IN 51 implementation.