Monitoring of cleanliness and disinfection in dairies: Comparison of traditional microbiological and ATP bioluminescence methods

The levels of aerobic contamination at different points in the production chain (curd vat, filler, mould, table and tank) at five cheese factories were analysed using contact plates, dipslides and bioluminescence methods. Almost all the cheese factories showed similar levels of contamination. ATP bioluminescence detected the largest number of unacceptable surfaces (47.7%), followed by the contact plates (41%) and dipslides (34.2%). The dipslide and contact plate methods showed moderate concordance and significant differences (p < 0.001) between the various surfaces sampled. The points in the production chain were classified according to contamination rates, being minimal in the curd vats–fillers and maximal in tables–moulds. The same surfaces were also sampled to determine total Enterobacteriaceae, mould and yeast growth using contact plates and dipslides and no concordance between these two methods was detected. These results were analysed and discussed taking into account the importance of cleanliness and disinfection in cheese factories, as a prerequisite of the HACCP (Hazard Analysis of Critical Control Points) quality assurance system.