Listeria monocytogenes - knowledge check

Listeria monocytogenes: In or not in?

Seminar sustainable packaging

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:

Training LMHV-4 Poultry Thermometer
  • 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

Where is L. mono particularly common in the environment?
On floors / in the floor area and on objects in contact with the floor.
Where should you always test?
Always test the gully area for L. mono - because if the germ is present in the production environment, it will sooner or later end up in the gully.
Do you remember why biofilm must always be removed as soon as possible?
The older the biofilm, the more difficult it is to remove.
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