Swiss Federal Dairy Research Station, Bern-Liebefeld

Risk assessment of L. monocytogenes in Swiss Emmental raw milk cheese

About 33% of the total Swiss agricultural earnings are from the milk production which is important to the Swiss agricultural industry. Our approach follows the origin and propagation of Listeria monocytogenes-contamination using data and expert-knowledge at all involved production levels and competence areas. The result is shown in a contamination profile along the food production chain of Swiss Emmental cheese made from raw milk. The decline in bacterial counts during cheese manufacture mainly depends on the cooking temperature. The reduction of L. monocytogenes on the rind of cheese is mainly due to the specific treatment of contaminated batches consisting in removal of contaminated rind, production of processed cheese or disinfecting. Specific treatments apply to 52-99% of totally manufactured Swiss Emmental cheese. Depending on listeria evolution from press to product consumption, consumer exposition might result in 1 to 10 Listeria monocytogenes /cheese-portion. Bacterial presence is explained with recontamination during packaging, distribution and cheese preparation by consumers. The consumption of traditional manufactured Swiss Emmental cheese represents an extremely low risk to all consumers, including consumer subgroups “at risk”.

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