Microbiological quality of raw milk: community expansion tanks in Alagoas

Milk is a highly nutritious food consumed by a large part of the population, and due to its nutritional composition, its quality can be altered by the amount of microorganisms present. The objective of this study was to evaluate the microbiological quality of raw milk from community expansion tanks in the state of Alagoas. A total of 160 milk samples were aseptically collected from the three mesoregions of the state for microbiological analysis. It was observed that 10.83% (13/120) of the samples had Staphylococcus coagulase-positive counts lower than 105 CFU/mL, and 10.83% (13/120) had counts higher than 105 CFU/mL. For coliforms, 18.8% (30/160) were found to have counts less than 1.1×103 MPN/mL, while 81.2% (130/160) of the samples had values higher than 1.1×103 MPN/mL. No Salmonella spp. or Listeria spp. were found in any of the samples. Aeromonas spp. was found in 28.7% (46/160) of the samples. For mesophilic microorganisms, 15% (24/160) of the samples were within the standard required by legislation, while 85% (136/160) were outside the established limit of up to 6×105 CFU/mL. Psychrotrophic microorganism counts were higher than 5×106 CFU/mL in 41.9% (67/160) of the samples analyzed. It was concluded from this study that the high microorganism counts in the analyzed milk and the inadequate temperature of the tanks at the time of collection can lead to the production of a low-quality product due to the deteriorative or pathogenic action of the microorganism. Therefore, the implementation of good practices during milking, transportation, and storage of refrigerated raw milk is suggested to prevent contamination of the raw material, ensuring a product with certified quality.