Listeria spp., coliformes, bactérias mesófilas e psicrotróficas no leitein natura e pasteurizado tipo C / Listeria spp., coliforms, mesophilic and psychrotrophic bacteria in raw and type C pasteurized milks

RESUMO

A qualidade microbiológica de 30 amostras de leite in natura e 30 de leite pasteurizado tipo C,provenientes da bacia leiteira do Médio Mearim/MA, foi avaliada por meio de análises de coliformes a 35 ºC e 45 ºC, contagem de bactérias aeróbias mesófilas e psicrotróficas e pesquisa de Listeria spp. O leite in natura apresentou contagem elevada de coliformes a 35 ºC e 45 °C (1,5 x 102 a >1,1 x 103 NMP/mL; <3 a >1,1 x 103 NMP/mL), bactérias mesófilas (2,8 x 104 a 2,2 x 106 UFC/mL) e psicrotróficas (5,2x 104 a 2 x 106 UFC/mL). Listeria spp. foi observada em 10 % (n=03) das amostras. As amostras de leite pasteurizado tipo C, 96,66 % (n=29) e 86,66 % (n=26) mostraram discordância com a Instrução Normativa 51, respectivamente, para coliformes a 35 ºC e 45 °C. Para as bactérias mesófilas, 100 % das amostras estavam em acordo com a legislação. As contagens de bactérias psicrotróficas foram expressivas com valores de 1,5 x 102 a 2,5 x 104 UFC/mL e ausência de Listeria spp. Os resultados sugerem que o leite in natura e o pasteurizado tipo C foram produzidos e processados sob condições higiênico-sanitárias insatisfatórias, com risco de veiculação de Listeria spp. por meio de leite in natura.(AU)

ABSTRACT

The microbiological quality of 30 samples of raw and 30 type C pasteurized milks, from the dairy regionof the Medium Mearim/MA, was assessed by analyzing coliforms at 35 ºC and 45 ºC, mesophilic aerobicand psychrotrophic bacteria counting, and Listeria spp. detection. The raw milk showed higher counts for coliforms at 35 ºC and 45 °C (15 x 102 to >1.1 x 103 MPN/mL; <3 to >1.1 x 103 MPN/mL), mesophilic bacteria (2.8 x 104 to 2.2 x 106 CFU/mL) and psychrotrophic bacteria (5.2 x 104 to 2 x 106 CFU/mL). Listeria spp. was found in 10 % (n=03) of samples. Among the type C pasteurized milk samples, 96.66 % (n=29) and 86.66 % (n=26) did not comply with IN 51 for coliforms at 35 ºC and 45 °C, respectively. For mesophilic bacteria, 100 % of samples were in agreement with the legislation. Psychrotrophic bacteria counts were significant with values from 1.5 x 102 to 2.5 x 104 CFU/mL, and no Listeria spp. was detected. These findings suggest that the both raw and type C pasteurized milks were produced and processed under unsatisfactory sanitary conditions, with risk of transporting Listeria spp. through the raw milk.(AU)