MEASUREMENT OF MICROBIOLOGICAL QUALITY OF RAW GOAT´S MILK BY LASER FLOW CYTOMETRY

Abstract

The popularity of goat's milk and its products is growing in Slovakia. Among the mandatory health safety features of raw goat's milk is the total bacterial count. It can be determined by the anchor plate-cultivation method, which is, however, tedious, and laborious. Laser flow cytometry is a modern alternative method for measuring the microbiological quality of raw milk. To use the results from laser flow cytometry method for legislative purposes, it is necessary to create a representative conversion of the primarily measured results obtained by this method into the CFU/mL scale. This work describes the creation of such a conversion for raw goat's milk, which will be valid for the Slovak region. After measuring several hundred individual and bulk tank samples of raw goat's milk on a BactoScan FC laser flow cytometer and at the same time using the anchor method according to STN EN ISO 4833-1 and after their subsequent logarithmic transformation, such a conversion was created in the form of log₁₀(CFU/mL) = 1.0174 x log₁₀(IBC/ml) + 2.7483. Subsequently, this was verified by comparing the recalculated and directly measured results in CFU/mL, using additional data set of samples. The influence of the somatic cell count in raw goat's milk, as a possible interfering factor, was also assessed.