MICROBIOLOGICAL QUALITY PARAMETERS OF PACKAGING MATERIALS USED IN THE DAIRY-INDUSTRY

The microbiological quality of various materials as used for packaging milk and dairy products was examined qualitatively and quantitatively. Arithmetical mean values of total aerobic mesophilic microorganisms associated with the surface of the packaging material were 33 CFU/cm2 (re-usable brown glass milk bottles), 0.13 CFU/cm2 (polyethylene caps), 1.0 CFU/100 cm2 (paper composite cartons and roll material), 5.6 CFU/100 ml of beaker content (polystyrene yogurt cups), 1.1 CFU/100 cm2 (polyethylene foil for Mozzarella cheese packaging). Paper board covers as used for the transportation of cheese varieties were investigated as homogenates and turned out to contain relatively higher numbers of bacteria as well as moulds than the remainder. The microbial population of this category of materials was represented mainly by aerobic spore-formers (arithmetical mean value: 2.8 x 10(5) CFU/g). With the exception of some Bacillus cereus positive results detected with glass bottles and board, no pathogenic microorganisms (E. coli, Salmonella sp., Listeria sp., Staphylococcus aureus, potentially mycotoxigenic moulds) were found with the samples. In this study, differences regarding the microbiological load (bacterial as well as yeast and mould counts) between new and used glass bottles after routine cleaning in a dairy plant, between paper composite cartons and roll material, and among cartons from different package suppliers are also presented.