CBT, IBC, Bactoscan, cytometry, quality milk
The dairy industries in Ecuador, in response to the social demand for quality products, implement control programs that demand more laboratory analysis such as the total bacteria count (TBC) as a parameter of the hygienic quality in raw milk, which is the most requested. However, the reference method for plate count has some limitations mainly in terms of the time needed to deliver the results. Flow cytometry is a rapid analytical method used for defining bacterial populations by Individual Bacteria Count (IBC/ml). The aim of the study was to determine the linear regression equation between the reference method and the alternative method by flow cytometry. A total of 357 milk samples with a range from 100,000 to 1,500,000 UFC/ml coming from of two altitudinal floors Z1 (> 3 000 masl) and Z2 (1 050 masl) were used. The results showed a high correlation between the methods (r = 0.91) and the linear equation for the Bactoscan FC calibration curve was defined for the total bacteria count with results expressed in UFC/ml. As no significant statistical differences were found, the effect by zones (Z1 and Z2) was not considered, suggesting the use of a single equation.