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Effectively combating Listeria in biofilms: New research strengthens the preventive approach in challenge tests

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Jul 1, 2026 - Foods

Effectively combating Listeria in biofilms: New research strengthens the preventive approach in challenge tests

Effectively combating Listeria in biofilms: New research strengthens the preventive approach in challenge tests

Listeria monocytogenes is one of the most critical foodborne pathogens. The number of public product recalls due to Listeria contamination has been increasing for years. Pregnant women, the elderly, and immunocompromised individuals are particularly at risk. An infection can have severe consequences, including miscarriages, premature births, and life-threatening illnesses.

A particular challenge for food businesses is that Listeria monocytogenes can settle in biofilms. These form preferentially in hard-to-reach areas such as drains, seals, or inadequately cleaned slicing machines. Within these biofilms, the bacteria are significantly more resistant to environmental influences and cleaning and disinfection measures.

Biopeptides as a promising research approach
New research results from a Thai research group show an innovative way to combat such biofilms. The scientists examined the culture supernatant of a harmless strain of Lactiplantibacillus plantarum and identified the antimicrobial biopeptide Plantaricin J in it.

The current study demonstrated that the plantaricin-containing culture supernatant effectively inhibits and reduces bacterial biofilms on food-contact surfaces. In addition to Listeria monocytogenes, other food-relevant microorganisms were also affected. The results highlight the potential of natural antimicrobial peptides as a future supplement to existing hygiene concepts in the food industry.

New EU requirements increase the need for action
The scientific findings coincide with a tightened regulatory situation. With the enactment of Regulation (EU) 2024/2895 on July 1, 2026, the requirements for proving food safety in ready-to-eat foods have been further specified.

Manufacturers must now provide more comprehensive evidence that Listeria monocytogenes cannot multiply to health-relevant concentrations during the entire shelf life of their products. In this context, challenge tests are becoming significantly more important.

Challenge tests provide security
Challenge tests examine the growth behavior of Listeria monocytogenes under realistic storage conditions. For this purpose, several independent production batches are deliberately inoculated with defined strains of Listeria and microbiologically tested throughout the entire shelf life.

The results show, among other things,

The investigations thus provide a scientifically sound basis for classifying ready-to-eat foods according to the microbiological criteria of European legislation.

A challenge test is not required for every product. Often, factors such as pH, aw-value, formulation, or robust scientific data already allow an assessment of the growth potential. However, if these proofs are not sufficient, challenge tests often represent the safest way to meet the legal requirements.

Prevention begins with the right investigation strategy
The fight against biofilms, effective hygiene management, and a well-founded assessment of the growth potential of Listeria monocytogenes are more important than ever today. Moreover, modern molecular biological rapid methods enable early detection of possible contaminations and sensibly complement classic microbiological examinations.

Would you like to know whether a challenge test is necessary for your products or which investigation strategy meets the new legal requirements? Our experts are happy to offer you individual advice and support you in planning and conducting appropriate verifications.

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