Evaluation of enterobacteriaceae in the powdered milk production chain using both traditional (ISO 21528:2) and rapid (3M™ Petrifilm™) methods

Abstract

This study sought to evaluate the presence of Enterobacteriaceae in several points of the powdered milk production chain (raw milk, pasteurized milk, powdered milk, and swabs of equipment and the hands of manipulators). There was a similarity between the ISO 21528:2 and the 3M Petrifilm Enterobacteriaceae Plate (EB) methods in all the samples tested. Enterobacteriaceae counts in raw milk were higher (p<0.001) than in other samples. Bacterial counts were similar for both sampling methods (p<0.01), except for raw milk. This observation highlights the fact that these samples were the main source of Enterobacteriaceae in the plant and reinforces the efficacy of the thermal treatment to reduce them. The mean Enterobacteriaceae counts were 5.68 and 5.83 log CFU/mL in raw milk and 0.45 and 0.97 log CFU/mL in powdered milk for the 3M Petrifilm EB plate and ISO 21528:2 methods, respectively. The industry used in this study can be considered a potential exporter of milk powdered to the European Union in terms of Enterobacteriaceae counts. © Springer-Verlag and the University of Milan 2010.