Challenge Test for Listeria monocytogenes – New Service at Sample Control Laboratory
Sample Control laboratory has expanded its service portfolio and has started conducting challenge tests for the bacterium Listeria monocytogenes in food products.
A challenge test is a specific microbiological study used to assess whether the bacterium Listeria monocytogenes can grow during the declared shelf life of a product. This type of testing is particularly important for ready-to-eat products (RTE – ready-to-eat products), as Listeria monocytogenes can grow even at refrigeration temperatures and poses a serious risk to consumer health.
Regulatory requirements
Commission Regulation (EU) 2024/2895 of 20 November 2024 amending Regulation (EC) No 2073/2005 with regard to the bacterium Listeria monocytogenes shall apply from 1 July 2026.
For ready-to-eat foods that support the growth of Listeria monocytogenes, excluding infant food and food for special medical purposes, the criterion “absence in 25 g” applies in all cases where the food business operator cannot satisfactorily demonstrate to the competent authority that the limit of 100 cfu/g will not be exceeded during the product’s shelf life.
The criterion of 100 cfu/g may only be applied if the food business operator can demonstrate to the competent authority that the specified limit will not be exceeded throughout the shelf life, whereby a challenge test is considered the only satisfactory proof.
How is a challenge test performed?
During the testing process, the product is artificially inoculated with a defined number of Listeria monocytogenes bacteria, using several different bacterial strains in order to simulate realistic contamination conditions. The samples are then stored under conditions corresponding to the declared shelf life of the product, while bacterial growth is monitored through predefined time points using microbiological analyses.
At the end of the study, the results are compared with the initial condition, and a conclusion is made as to whether the product supports the growth of Listeria monocytogenes or not.
Implementation in accordance with relevant standards
Sample Control provides professional support to food business operators in assessing the need for a challenge test and prepares the experimental testing protocol in accordance with:
HRN EN ISO 20976-1 standard
EURL L. monocytogenes technical guidelines
Quantitative analysis of Listeria monocytogenes is performed according to the accredited HRN EN ISO 11290-2 method.
Monitoring throughout the entire shelf life
As part of the challenge test, the laboratory also determines relevant physicochemical parameters such as pH value and water activity, as well as verifies the natural microflora and possible natural contamination.
The laboratory independently prepares the inoculum from a mixture of bacterial strains, performs product inoculation, repackaging under original conditions, incubation, and final interpretation of the results.
Are you developing a new product or would you like to confirm the safety of an existing RTE product? Contact us via the contact form — our team will help you assess the need for a challenge test and define the optimal testing plan.
Migration of Substances from Packaging into Food
Migration of substances from packaging into food represents the process of transfer of chemical compounds from packaging material into a food product during storage, transport, or food preparation. Packaging can be made of different materials such as plastics, paper and cardboard, glass, metals, and multilayer materials.
Presence and contamination of meat with perfluoroalkyl (PFAS) compounds
Perfluoroethyl compounds (PFAS) is a collective term for a very large group of fluorinated compounds, including oligomers and polymers, consisting of neutral and anion surface active compounds with high heat, chemical and biological inertness. Perfluorinated compounds are generally hydrophobic but also lipophobic and therefore will not accumulate in fat tissues as is usually the case with other persistent halogenated compounds. An important subgroup are (per) fluorinated organic surfactants, including perfluorooctane sulfonate (PFOS) and perfluorooctane acid (PFOA). For PFOS and PFOA, the European Food Safety Authority (EFSA) established a tolerable daily intake (TDI) for humans of 150 ng/kg body weight and 1.5 μg/kg body weight per day (EFSA 2008).