Listeria in Food Production: Risks, Control Measures, and Spectral Blue MWHI® Solutions

Listeria monocytogenes is a major concern for food processing companies because it thrives in cool, moist environments, making food processing plants particularly vulnerable. It can survive refrigeration and even freezing temperatures, which means it can easily contaminate ready-to-eat products, dairy, meat, and seafood. Once Listeria enters the production environment, it can be difficult to eliminate, leading to recalls, business shutdowns, and serious public health risks.

This article covers key things to know about Listeria and key considerations in controlling Listeria contamination in food production environments. We also highlight why blue light is an ideal solution for eradicating Listeria contamination.

Key Takeaways

  • Persistent Threat: Listeria monocytogenes poses a significant risk in ready-to-eat (RTE) food production due to its resilience in cold and moist environments.
  • Limitations of Traditional Methods: Standard hygiene protocols and chemical disinfectants may not fully eliminate Listeria contamination.
  • Innovative Solution: Spectral Blue MWHI® blue light technology offers an effective, chemical-free method to automatically reduce Listeria presence on surfaces.
  • Proven Results: Case studies demonstrate significant reductions in Listeria  monocytogenes contamination when deploying Spectral Blue devices.
  • Regulatory Compliance: Utilizing Spectral Blue technology can aid in meeting stringent food safety standards and regulations.

On this page:

What is Listeria?

Listeria monocytogenes is a bacterium that can cause listeriosis, a serious infection primarily affecting pregnant women, newborns, older adults, and individuals with weakened immune systems. Unlike many other pathogens, Listeria can thrive in cold environments, making it a persistent concern in refrigerated foods.

Risks in Food Production

In the food industry, particularly in RTE food production, Listeria monocytogenes poses a significant threat due to its ability to:

  • Survive and grow at refrigeration temperatures.
  • Form biofilms on equipment surfaces, making it resistant to standard cleaning procedures.
  • Contaminate products post-processing, especially in environments with inadequate sanitation controls.

High-risk foods include: 

  • Deli meats and cured meats.
  • Soft cheeses like brie and camembert.
  • Smoked seafood products.
  • Pre-cut fresh produce.

Listeria contamination was the most common biological cause of product recalls in the USA from 2002 to 2023 (DeBeer et al., 2024). In the EU, the number of confirmed listeriosis cases has shown an alarming upward trend between 2007 and 2023 (ECDC Surveillance Atlas of Infectious Diseases).

Traditional Control Methods

Traditional methods to control Listeria in food production involve:

  • Chemical Disinfectants: Use of chlorine-based or quaternary ammonium compounds.
  • Thermal Processing: Applying heat to eliminate pathogens.
  • Good Manufacturing Practices (GMPs): Implementing hygiene protocols and regular equipment cleaning.

However, these methods have limitations:

  • Chemical residues may remain on equipment or products.
  • Heat treatment is not applicable to all products, especially RTE foods.
  • Biofilms can protect Listeria from disinfectants, allowing it to persist in the environment. Often very high chemical concentrations are required.
  • Episodic disinfection (wiping surfaces once per day) is often not enough to prevent regrowth.

Spectral Blue MWHI® Solution

Spectral Blue MWHI® technology utilizes multi-wavelength high-intensity blue light (405–450 nm) to inactivate Listeria monocytogenes on surfaces. This chemical-free approach offers several advantages:

  • Automatic Method: Once installed, the Spectral Blue devices work without user input.
  • Effective and Safe Disinfection: Targets and destroys microbial cells without harming staff, equipment or products.
  • Effective against Biofilms: Can eliminate colonies residing in biofilms and on moist surfaces.
  • Continuous Operation: Can be used even during production without interrupting processes. Use a presence sensor to turn devices off when people are near.
  • No Chemical Residues: Eliminates concerns about residual chemicals on food contact surfaces.
  • Alternate Mechanism of Action: Spectral Blue enhances your existing cleaning and disinfection practices by adding an independent antimicrobial mechanism.
  • Environmentally Friendly: Reduces the need for water and chemical usage in sanitation.

Case Study: Ready-to-Eat (RTE) Food Production Facility (2025)

In a Central European ready-to-eat food production facility, implementing Spectral Blue MWHI® technology led to a significant reduction in Listeria monocytogenes contamination at a production line. The study, presented at the IAFP European Symposium on Food Safety 2025, highlighted:

  • A significant decrease in Listeria monocytogenes presence on production surfaces.
  • Improved overall hygiene and sanitation levels.
  • Enhanced compliance with food safety standards.

For detailed insights, refer to the full article: Tackling Listeria in Food Production: Success with Spectral Blue MWHI® Blue Light

Laboratory Validation

Laboratory tests have validated the efficacy of Spectral Blue MWHI® technology against Listeria monocytogenes. Key findings include:

  • Significant reduction of Listeria populations on various surfaces.
  • Effectiveness across different environmental conditions.
  • Compatibility with existing cleaning protocols, enhancing overall sanitation efforts.

For detailed test results, please see laboratory tests with Spectral Blue and peer-reviewed general laboratory tests with blue light.

Regulatory Updates: EU Regulation (2026)

In response to increasing concerns about Listeria monocytogenes in ready-to-eat (RTE) foods, the European Commission has introduced Regulation (EU) 2024/2895, which amends the foundational food safety law Regulation (EC) No 2073/2005 on microbiological criteria for foodstuffs.

The updated requirements, coming into force on July 1, 2026, significantly strengthen expectations for Listeria monocytogenes control across the entire food chain. Key changes include:

Stricter Microbiological Limits

RTE foods that support the growth of Listeria monocytogenes must not contain detectable levels (0 cfu/25g) at any point during their shelf life, unless the food business operator can scientifically demonstrate that the levels will remain below 100 cfu/g throughout the product's shelf life.

This raises the compliance bar for many cold-stored or moisture-rich products.

Extended Legal Responsibility

For the first time, responsibility for Listeria control extends beyond manufacturers to include distributors, transporters, and retailers.

Every actor in the food supply chain must verify that their practices help maintain microbiological safety until the point of consumption.

Enhanced Monitoring and Corrective Action

Food business operators must carry out routine testing, maintain detailed records, and implement corrective actions promptly when Listeria monocytogenes is detected.

This encourages continuous monitoring, not just end-product testing.

These amendments reflect a shift toward a more holistic, chain-wide responsibility for microbiological safety. Technologies like Spectral Blue MWHI®, which can reduce Listeria in production environments without chemicals or UV, provide proactive tools to help food producers meet these stricter EU requirements.

Conclusion

Listeria monocytogenes remains a critical concern in food production, particularly for RTE products. Traditional control methods have limitations, and the recent EU regulatory updates necessitate more stringent measures.

Spectral Blue MWHI® technology offers an effective, chemical-free solution to enhance Listeria control, aiding food businesses in meeting regulatory requirements and ensuring consumer safety.

References

  1. SGS Digicomply Editorial Team. (2025, May 27). New Listeria Criteria for Ready-to-Eat Foods: EU Regulation 2024/2895. Retrieved from SGS Digicomply.
  2. Henderson, B. (2024, November 21). EU Expands Responsibility for Listeria Criteria in RTE Foods to Additional Food Business Operators. Retrieved from Food Safety Magazine.
  3. Henricson, K., Autio, T., Schmidt, R., & Saukkonen, J. (2025). Automatic Disinfection of Listeria monocytogenes on a Sushi Production Line Using Multi-Wavelength High-Intensity (MWHI) Blue Light. Poster presented at the IAFP European Symposium on Food Safety, Madrid, Spain. Retrieved from Spectral Blue Blog.
  4. European Commission. (2024, November 20). Commission Regulation (EU) 2024/2895 of 20 November 2024 amending Regulation (EC) No 2073/2005 as regards Listeria monocytogenes. Retrieved from EUR-Lex.
  5. John DeBeer, Erika Rene Blickem, Yadwinder Singh Rana, Deborah Mona Baumgartel, Jon W. Bell, An Analysis of Food Recalls in the United States, 2002–2023. Journal of Food Protection, Volume 87, Issue 12, 2024,100378. https://doi.org/10.1016/j.jfp.2024.100378
  6. ECDC Surveillance Atlas of Infectious Diseases, https://atlas.ecdc.europa.eu/

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