Evaluation of physical, chemical and microbiological quality of raw and pasteurized grade A milk and points of contamination at a dairy farm in RS

Grade A milk is produced and processed by rigid and specific standard of quality. This research aimed to evaluate microbiological, physical and chemical characteristics of raw and pasteurized grade A milk and know some critical points of contamination at a dairy farm in Rio Grande do Sul. For November, 2006 to April, 2008 we carried out six visits and sample collection at the property. At each one, there were collected samples of raw and pasteurized milk, swabs of teats skin and milking machine liners. There were performed aerobic mesophiles counting and total and fecal coliforms (MPN). To raw milk, it was also performed psychrotropic counting. About total and fecal coliforms counting, 50 and 33.3% of the pasteurized milk samples were above the legal standard (IN 51). About aerobic mesophilic bacteria counting, 2 samples were considered inappropriate. Raw milk presented high aerobic mesophiles counting (>1.0 x 10(4) CFU/mL in 3 samples). At liners, we observed that counts increase between the first and the last sampling. The first raw milk and fifth pasteurized milk presented low fat percent (<3.0%). Somatic cells counts were higher than legal standard at five raw and one pasteurized milk samples. It is necessary to improve milk quality by correct milk and cow management to adequate production to the legal standards.