Listeria monocytogenes - knowledge check
Listeria monocytogenes: In or not in?
There are many measures to prevent Listeria monocytogenes in food.
The first is: knowing the properties of the germ.
Here you can test and refresh your knowledge.
Growth conditions Listeria monocytogenes
Do you remember the answers to the following questions? If not: press the black triangles to see the answer:
L. mono grows at a pH between pH 4.2 and 9.5.
Example food pH approx. 4.2: soft cheese
Example food pH approx. 9.5: salmon
L. mono can reproduce at a temperature from -1.5°C to +45°C.
The optimum is between 30°C and 37°C.
L. mono grows facultative anaerobic. Thus, the germ can grow with or without oxygen, even under a protective gas atmosphere.
L. mono grows at salt concentrations of <0.5 - 12 %. The germ can also survive at > 20 %.
This means that L. mono is very tolerant of salt.
Example foods with high salt content:
- Raw ham
– hard cheese
L. mono hardly needs any nutrients to survive. Even an occurrence in cooling water has already been observed.
Main preventive measures against L. mono
There is a great deal that can be done to prevent Listeria from spreading on the farm. Press the black triangle to see what the most important actions are:
- supplier management
- Avoid "retreat areas", eg defective floors
- Personal hygiene, training, awareness-raising
- Keep the environment clean and disinfect if necessary
- Clean and disinfect devices according to manufacturer specifications
- Sampling environment and food
- Prevent / combat biofilm
- Comply with temperature specifications
risk foods
- Ready-to-eat food due to recontamination during processing
- smoked fish
- Raw milk, raw milk products, soft cheese
- Raw sausage, raw minced meat
- Packaged salads
- Packaged sandwiches
risks in the environment
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