Listeria spp., coliforms, mesophilic and psychrotrophic bacteria in raw and type C pasteurized milks

Abstract

The microbiological quality of 30 samples of raw and 30 type C pasteurized milks, from the dairy region of the Medium Mearim/MA, was assessed by analyzing coliforms at 35 ºC and 45 ºC, mesophilic aerobic and 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.