Microbiological quality of raw milk sold directly from farms to consumers in Switzerland

Abstract

Seventy-three samples of raw cow milk marketed at farm level (12 pre-filled bottles, 61 from vending machines) were investigated for their microbiological quality and the occurrence of bacterial foodborne pathogens. Total viable counts (TVC) were mainly (67.1 %) in the range from 103 to 105 CFU/ml, while Escherichia coli and coagulase-positive staphylococci were each detected in 30.1 % of the samples. TVC results for raw milk from vending machines (34.4 % above 105 CFU/ml) were clearly higher than those from pre-filled bottles, emphasizing the importance of ensuring correct cleaning and disinfection procedures of vending machines. Moreover, regular monitoring of the microbiological quality of raw milk from vending machines should be considered. With regard to foodborne pathogens in raw milk marketed at farm level, 24.7 % of all samples were positive for Staphylococcus aureus harboring staphylococcal ­enterotoxin (SE) genes. Genes for SEA, SEC, and SED were thereby also detected. On the other hand, Campylobacter spp., Listeria monocytogenes, and Shiga toxin-producing Escherichia coli were not detected. But because the occurrence of foodborne pathogens can never be ruled out, raw milk should always be properly heated before consumption.