Evaluation of BactoScan FC for the enumeration of bacteria in raw milk [French]

摘要

The evaluation of BactoScan FC for routine enumeration of bacteria in raw milk was carried out according to the model proposed by the International Dairy Federation. The linearity of response of BactoScan FC was verified between 6 000 and 27 000 000 pulses.mL(-1) without reaching the limits of detection which have not been determined. The transmission error was estimated at 0.09% and the repeatability at 0.084 log(10) CFU.mL(-1) for a 60 000 CFU.mL(-1) mean level of contamination. The stability of the equipment over time was verified; in both the short term and the long term, reproducibility is in the same order of magnitude as repeatability. The relationship between BactoScan FC and the reference method is linear over the whole range analysed (700 to 26 000 000 CFU.mL(-1)), with a determination threshold estimated at under 4 000 CFU.mL(-1). The regression equation between the reference method and the BactoScan FC is: log(10) (CFU.mL(-1)) = 0.839 x log(10) (pulses.mL(-1)) + 0.095. The accuracy of estimation of the reference value, expressed by the residual standard deviation of the regression, is 0.287 log(10) CFU.mL(-1). Finally, the independence of this estimate compared to the somatic cell level of the samples was verified.