Listeria under control: why challenge testing is a priority now

13 May 2026

New regulations require clear evidence that Listeria monocytogenes remains under control throughout a product's shelf life. Challenge testing provides the scientific validation needed to demonstrate compliance and protect consumers.

First, it is good to set the background. Regulation 2073/2005 establishes two key criteria for Listeria in ready-to-eat foods: first, the criterion that L. monocytogenes should not be detectable in 25 g for products in which growth may occur, before the product leaves the operator; second, the limit of 100 cfu/g over the entire shelf life if growth of Listeria is shown not to occur.

For many RTE products, this leads to the need to substantiate whether or not growth is possible. The mechanism to substantiate growth includes a challenge test or shelf-life/growth potency study, as described in the technical guidelines of the European Union Reference Laboratory Listeria monocytogenes (EURL Lm).

With the announced regulatory change, these requirements will become more realistic, concrete and verifiable. For a QA manager, this means that it is no longer enough to rely on general process control; legislators and regulatory bodies expect explicit evidence of the growth potential of L. monocytogenes in the product throughout its shelf life. The Belgian Federal Agency for the Safety of the Food Chain (FASFC) clarified this in a circular "regarding Listeria monocytogenes in ready-to-eat foods."

Therefore, it is crucial for quality managers in both the Netherlands and Belgium to now proactively integrate challenge testing into product validation, revise processes and protocols based on the new guidelines, and internally ready the knowledge and cooperation with laboratories.

What does this mean practically for the industry?

For a QA manager, it is important to properly set up the internal process for challenge testing - from product selection over worst-case scenarios to reporting - and to do so in line with the methodology prescribed by regulators and the EURL. For example, the Dutch Food and Consumer Product Safety Authority (NVWA) Food Microbiology Handbook describes that for a growth potential study, at least three different batches are tested, with multiple samples within a batch, and that for a MAP package, both the initial and final parameters (such as composition, aw, pH) should be tested. Also, the choice of Listeria strains should be substantiated (preferably strains from the EURL collection) and the temperature-time profile should be representative of realistic storage, distribution and preservation conditions.

In addition, for the Belgian context, the FASFC circular plays a key role: it clarifies under which conditions an operator can suffice with the criterion 100 cfu/g instead of "not detectable in 25 g". For example: when a product does not support growth (at pH ≤ 4.4 or aw ≤ 0.92) or when a challenge test has shown that growth does not occur.

Laboratory testing of packaged fruits and vegetables for food quality control.

As a QA manager, you should therefore:

Screen the product portfolio: which products fall under "growth possible" versus "growth not possible"?
Define worst-case scenarios: which product/process conditions could lead to growth?
Select laboratory partners experienced in challenge testing according to EURL-TGD and national guidelines
Set up the evidence file: reporting, validation report, batch variation analysis, temperature profiles
Tighten internal procedures & HACCP structure such that challenge testing is part of the validation process

Foodlab Foodcontrol

European context and development

Within other EU member states, the same framework of Regulation 2073/2005 and its EURL guidelines is being followed. For example, the Food Safety Authority of Ireland (FSAI) published a "Guidance Note No. 27" which explicitly mentions challenge testing and shelf-life studies as part of operators' obligations to demonstrate compliance with microbiological criteria during shelf-life.

This European harmonization means that companies with exports to other member states or international supply chains cannot follow a separate national interpretation, but must comply with the harmonized criterion and evidence. So this makes it even more relevant for QA managers to think at the EU level.

Why this change demands attention and what the deadline means

Specifically, the change effective June 2026 means for the industry: timely incorporation of challenge testing, risk assessment and documentation. Clearly, proof that growth of L. monocytogenes does not occur or that the 100 cfu/g limit is guaranteed during shelf life will take center stage.

For the QA manager, this means that the current moment should be used as a "window of opportunity" to bring internal processes, knowledge and cooperation with laboratories to the right level, so that when the change is implemented there is no backlog. Therefore, it is also prudent to include planning, budgeting and strategic prioritization for challenge testing in the quality process.

Controlling Listeria in RTE products is not new, but the combination of tightened regulations, explicit evidence through challenge testing and European harmonization makes this a hot topic for QA managers in the Netherlands and Belgium at the moment. By investing now in the right methodology-conform EURL TGD, NVWA manual, FAVV circular-you are laying a solid foundation for compliance and for food safety within your organization.

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