Psichrotrophics bacteria counting in bovine raw milk using standard method and Compact Dry® system

Abstract

The bulk milk has resulted in the reduction of the countings of mesophilics bacteria in milk. However, microorganisms that survive in low temperatures as the psichrotrophics bacteria became more relevant. These microorganisms are responsible for modifications in the milky products, intervening with its sensorial and reological characteristics and reducing the shelf life. The aim of this study was to count psichrotrophics microorganisms in bovine raw milk and analyze the performance of Compact Dry® for counting these microorganisms. From the analyzed samples, 18 (94.7%) showed equal or higher countings than 10⁵ UFC.mL^-1 and in 1 (5.2%) sample, the number of psichrotrophics was inferior to 104 UFC.mL-1, for both methods. According these results it is necessary to improve the sanitary quality of raw milk. Simple regression analysis of data showed a strong correlation between standard method and Compact Dry® (r²>0.9) for determining the number of psichrotrophics, which suggests that Compact Dry® is suitable to be employed as alternative technique for microorganisms counting in raw milk.