Stricter listeria regulations: Impact on food safety and challenge testing

What do shelf life tests and stress tests involve?

Shelf life and exposure tests play a crucial role in ensuring food safety. These tests provide information on how microorganisms behave in a particular product throughout its shelf life under realistic conditions.

General shelf life tests simulate the storage conditions of a product to assess the growth of microorganisms. Samples are microbiologically tested at specific intervals to ensure food safety and quality throughout the shelf life.

In a challenge test, a product is infected with bacteria in a controlled manner and stored under conditions that are as close as possible to the reality of production, distribution and storage. During the test period, samples are analyzed at certain intervals to determine whether and to what extent the bacteria are multiplying.

Detailed product information is essential for successfully carrying out a challenge test. This includes the composition of the product, such as pH value, salt content and water activity, but also the packaging method and the specific storage conditions. In addition, past microbiological data plays an important role in designing a test that exactly matches the characteristics of the product.

Based on this data, the laboratory can create a test protocol that corresponds to the specific conditions of the product.

The performance of shelf-life and challenge tests specifically targeting the growth of Listeria monocytogenes has been described by the EU reference laboratory in the TECHNICAL GUIDELINES DOCUMENT (TGD) on challenge tests and shelf-life studies to assess the shelf-life of ready-to-eat foods in relation to Listeria monocytogenes.

Why was the TGD for Listeria monocytogenes created?

The TGD developed by the EU Reference Laboratory for Listeria monocytogenes provides a harmonized approach for performing the above mentioned tests. This document should now be read in conjunction with the standard EN-ISO 20976-1 Microbiology of the food chain - Requirements and guidelines for the performance of challenge tests on food and feed. The aim is to ensure food safety and enable businesses to comply with Regulation (EC) No 2073/2005.

The TGD plays an essential role in improving the reliability and reproducibility of microbiological testing and ensures that results are consistent and of high quality. In addition, it ensures that tests reflect the complexity of ready-to-eat foods, which often present unique challenges. Finally, the guide helps companies demonstrate compliance with regulatory criteria - a crucial step in ensuring food safety.

An important part of the TGD is the careful consideration of variability within and between batches. It is therefore recommended to test at least three different production batches in preparation for the challenge test and to analyze at least five samples within each batch for aW, pH and salt, among others. One to three intermediate measurements are mandatory as part of the challenge test. In addition, the challenge test should be started within 48 hours of production. This provides a better picture of the microbiological risks and a representative assessment.

In addition, great importance is attached to realistically mapping the entire food chain. This means that the storage conditions during the challenge tests are extended, including the simulation of temperature fluctuations that can occur in real situations. This approach replicates production, distribution and consumer storage conditions as closely as possible.

An exception for consumer temperature applies to Belgium. In challenge tests for the Belgian market, it is set at 9°C, while for other EU markets it is set at 10°C.

The selection of Listeria monocytogenes strains for challenge testing is another issue. The guideline recommends selecting strains that are relevant to the product type, preferably strains that have previously been implicated in outbreaks. This ensures that the tests correspond to the actual risks.

Finally, it is emphasized that companies should use accredited laboratories that have the expertise and infrastructure to perform these complex tests. This is important not only for the reliability of the results, but also for compliance with laws and regulations.

With these guidelines, food companies can not only improve food safety, but also prove with certainty that their products meet the stricter requirements.

Effects of the amendment to Regulation 2073/2005

One important change is the extension of responsibility. Not only manufacturers, but all food businesses in the chain must prove that their products meet the microbiological criteria throughout their shelf life. This requires close monitoring and control of all links in the chain.

In addition, the criteria for products that promote the growth of Listeria monocytogenes have been tightened. This bacterium must not be detectable in 25 grams of product during the entire shelf life, unless it can be proven that the limit of 100 CFU/g is not exceeded. This stricter monitoring applies from production through distribution to storage.

For quality managers, this means that shelf life and exposure tests will become increasingly important, but also more complex. More companies will have to carry out such tests to prove the safety of their products. These tests will need to replicate the entire chain, including batch variability and realistic storage and distribution conditions. Methods for detecting Listeria monocytogenes in 25 g of product will become more important.

The changes often require modifications to existing test protocols. These include a more comprehensive simulation of storage conditions and a stronger focus on reliability in the design of challenge tests.

Companies have until July 1, 2026 to adapt to the new regulations. This gives them the opportunity to revise or supplement existing tests and work with specialized laboratories.

The new requirements underline the importance of a strong food safety strategy. By acting in a timely manner and investing in reliable testing, quality managers can not only comply with regulations but also contribute to the safety and quality of the food chain.

While this requires an investment in time and resources, it also offers opportunities. By working closely with the laboratory and utilizing their expertise in challenge testing, your company can not only comply with regulations, but also take its food safety management to the next level.

Conclusion

The amendment to Regulation (EC) No 2073/2005 underlines the crucial role of microbiological testing in ensuring food safety. Quality managers in the food industry are challenged to improve their knowledge and procedures. By working closely with specialized laboratories, companies can not only meet the new requirements, but also contribute to a safer food system for consumers.

Do you have any questions about the new regulations or would you like to find out more about shelf life and stress testing? We are happy to support you with expert advice and customized solutions. Please contact us at food@gba-group.de