What should be considered when conducting stress or challenge tests with Listeria monocytogenes?

What should be considered when conducting stress or challenge tests with Listeria monocytogenes?

What should be considered when conducting stress or challenge tests with Listeria monocytogenes?

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A technical guideline (EURL Lm TECHNICAL GUIDANCE DOCUMENT for conducting shelf-life studies on Listeria monocytogenes in ready-to-eat foods) was published by the EU Commission, which describes the procedure for conducting challenge tests with Listeria monocytogenes.

Some important aspects of it:

  • The conditions during the shelf life must be considered (including foreseeable changes compared to the information on the packaging, such as refrigerator temperatures in households).
  • A mixture of at least 2 strains of Listeria monocytogenes should be used for contamination. Not only laboratory strains should be used, but also strains isolated from similar foods or even from the respective food company.
  • The food should be contaminated at the beginning of the challenge test with a germ concentration of about 100 CFU/g.
  • DIN EN ISO 20976-1:2019-09 (https://www.beuth.de/de/norm/din-en-iso-20976-1/297296778)