Evaluation of Steel Surface Cleanliness Level in Dairies Using the Bioluminescence Method

The aim of the study was to evaluate the usefulness of bioluminescence in the determination of cleanliness of steel surfaces characterised by different roughness (0.6 and 0.8 μm). The applicability of the method was assessed based on correlations between the number of relative light units (RLU) measured with a luminometer and microbial counts determined by the conventional microbiological method (cfu/cm). The higher the roughness of surface was the higher was the microbiological contamination measured by these methods. Microbial counts classifying an examined surface as clean, acceptably clean and unacceptable clean were the basis for predictions of RLU ranges. High levels of proportional correlation were obtained for these methods.