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Dec 22, 2025 - Foods
What are challenge tests with Listeria monocytogenes? – Part 3
In these tests, food is intentionally contaminated with specific strains of Listeria monocytogenes. The product is then stored under specified conditions (e.g., refrigeration) throughout the entire shelf life and examined at regular intervals. At the end of the test, the results are compared with the initial values to see if and to what extent Listeria monocytogenes has multiplied during the shelf life.
According to the specifications of the “Technical Guidance Documents on challenge tests and durability studies for assessing shelf-life of ready-to-eat foods related to Listeria monocytogenes” (Version 4, July 1, 2021), the test must be conducted on at least three independent batches. This ensures that the results are reliable, taking into account variations in batch homogeneity and the measurement uncertainties of the methods, and allow a safe conclusion about the growth behavior of the bacteria.
There are two different types of challenge tests: one to determine the growth potential and one to determine the growth rate.
The first test checks whether and to what extent Listeria monocytogenes can multiply under the given conditions. If the growth exceeds 0.5 log levels, the growth is considered favorable. However, if the growth remains limited to a maximum of 0.5 log levels in three batches, it means that the food does not support the growth of the bacteria. This statement is very important for the correct categorization of the food according to Annex I, Chapter 1 of Regulation (EC) No. 2073/2005.
The second test investigates how quickly Listeria monocytogenes can multiply in the product. With this information, intermediate limits for Listeria monocytogenes can be established. This test is particularly important for category 1.2 products, where the presence of Listeria monocytogenes cannot be excluded due to raw materials and at the same time growth in food is favored. By establishing such limits, recalls can be prevented.
You can find our profile on Listeria monocytogenes at the following link: https://www.bav-institut.de/en/faqs/what-is-the-significance-of-listeria-monocytogenes-in-foods
In our laboratory, we regularly conduct tests for Listeria monocytogenes and challenge tests with Listeria monocytogenes. We provide you with fast and reliable results.
Our customer advisors are happy to assist you with any questions.
Additional links:
BAV-Institut: Why are challenge tests with Listeria monocytogenes required? – Part 1:
BAV-Institut: Why are challenge tests with Listeria monocytogenes required? – Part 2: https://www.bav-institut.de/en/news/why-are-challenge-tests-with-listeria-monocytogenes-required-part-2
Lebensmittelverband Deutschland e.V.: https://www.lebensmittelverband.de/en/; Link to the guideline: https://www.lebensmittelverband.de/en/media/publication/guidelines-for-good-practice-recommendations-for-prevention-measures-against-listeria-monocytogenes-in-certain-areas-of-food-production
BfR - Federal Institute for Risk Assessment: https://www.bfr.bund.de/en/; Link: https://www.bfr.bund.de/en/listeria-54356.html
RKI – Robert Koch Institute: https://www.rki.de/EN; Link: https://www.rki.de/EN/Content/News/Publications/RKI-Guide/Guide/Guide_Listeriosis.html