Listeria Environmental Testing


    Environmental testing for Listeria genus can provide an early indicator of process gaps and contamination risks in your plant. Frequent and routine environmental testing can mitigate the risk of a positive test result for L. monocytogenes  in food samples, causing costly shut-downs and recalls.

    Today’s methods are neither timely or actionable, as shipping samples to an external lab can cause significant delays. Palladium™ can provide a clear result in about two hours*, allowing you to test and take action within the same shift. Palladium in-situ testing also prevents cross-contamination, eliminates the need for highly trained lab personnel, and allows for easy centralized reporting to detect trends.

    Current testing protocols range from 24 hours to 5 days. 

    “The biggest advantage is speed of detection,” eliminating the need to store product while awaiting results. 

    –Manager, Food Safety and Microbiology,

    While wet, cold and frozen foods are commonly seen as high risk for Listeria, recent changes to the FDA guidelines suggest more rigorous Listeria testing across food segmentsThe risk of Listeria growth is determined by several environmental factors:

    • Temperature
    • Water content
    • Oxygen
    • Acidity

    Dairy products, with a neutral pH and high water content, are considered at risk for Listeria.  This is due to the ability of L. monocytogenes to survive extreme conditions and cause food contamination, primarily during post-processing or post-pasteurization cross-contamination.  L. monocytogenes can attach to food contact surfaces and form biofilms, allowing it to survive in hostile environments.

    In meetings with food safety experts at market-leading food companies, Listeria in frozen food and cold food categories are of particular concern. While the cold temperatures of refrigerators or freezers can slow down the growth of Listeria cells and can be used to preserve food, it is not able to kill the bacteria. This puts foods that consumers are unlikely to heat after purchase at a particularly high risk. Environmental testing is a precautionary step that helps to mitigate the risk of contamination within the facility before it reaches the product. 

    Studies such as "An Insight into the Isolation, Enumeration, and Molecular Detection of Listeria Monocytogenes in Food" prove molecular methods like the DNA microarray technology used in Palladium™ are “rapid, sensitive, specific, and time- and labor-saving.” 

     *Not currently available in the U.S. 


    1.  Montville, Thomas J. “Food Microbiology.” Access Science, 2016,

    2. Law, Jodi Woan-Fei, et al. “An Insight into the Isolation, Enumeration, and Molecular Detection of Listeria Monocytogenes in Food.” Frontiers in Microbiology, vol. 6, 2015, doi:10.3389/fmicb.2015.01227.


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