Refrigerated raw milk quality of a processing plant in the north of Parana after the implementation of changes imposed by NI 62 of 2011

Resumo

This study aimed to compare the microbiological and physicochemical quality of raw milk from individual and collective tanks, identify the psychrotrophic microbiota of refrigerated raw milk and verify compliance with current legislation. The enumeration of proteolytic and lipolytic psychrotrophs, as well as, populations of mesophilic aerobes, total coliforms, E. coli and enterobacteria was carried out. The psychrotrophic microbiota was characterized by morpho-tinctorial tests. Determination of fat content, protein, lactose, total solids, titratable acidity, cryoscopic index and somatic cells count (SCC) were also conducted. The average counts of mesophilic aerobes did not met the minimum quality requirements; however, the average results of SCC and the physicochemical parameters were in accordance with Brazilian legislation. The psychrotrophs counts were on average 90% of the total count of mesophilic aerobes, with psychrotrophic population of less than 6 log CFU/ml. A high percentage of proteolytic and lipolytic psychrotrophs in relation to psychrotrophs total counts was found. Considering the two weeks testing, there was a significant difference (P> 0.05) between milk samples from collective and individual tanks only for total coliforms and for protein and lactose contents. Although the predominant psychrotrophic microbiota was Gram negative bacilli, but Gram positive bacteria were also found. Thus, the population of mesophilic aerobes in disagreement with the legislation and the high counts of psychrotrophic and Gram negative population in milk are indicative that yet, there are problems in the sanitary-hygienic production, storage and transportation of refrigerated raw milk produced in the region studied. Therefore, there is a gap between the practices recommended by legislation and the actions really found in the Brazilian milk production chain.