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Listeria monocytogenes

Listeria monocytogenes is recognized as a pathogen of concern in fresh produce handling and processing operations. While it may be isolated from produce growing environments, the potential for contamination and entrenchment in equipment heightens the need for operations to have strong environmental monitoring and sanitation control programs. Through training workshops and the development of guidance documents and various technical resources, United Fresh and members of our Food Safety Council strive to provide continuous support to the fresh produce industry on Listeria monitoring and control

For more information about Listeria resources, contact Dr. Jennifer McEntire or Dr. Emily Griep.

Listeria Training Resources

The Listeria Workshop

The Listeria Workshop will bring together attendees from various food companies, including growers, shippers, packers, retailers, suppliers and food safety consultants in the fresh produce industry. The Workshop itself will feature: general sessions on sanitary design, sanitation best practices and environmental monitoring with breakout sessions, panel discussions, case studies and much more! There will also be a networking reception event on the first night of the event and will feature table top displays from various industry exhibitors!

More workshops will be announced soon. To receive updates on when new courses are announced, complete this form.  

Listeria Workshop Information

Zone 1 Sampling

As Zone 1 sampling becomes more common within the fresh produce industry, increased guidance and training is needed to ensure testing is done properly. This page includes webinars and trainings, guidance documents, and other resources to provide support to the industry. 

Zone 1 Sampling Information

Strategies for Listeria Control in Tree Fruit Packinghouses

Environmental contamination by Listeria monocytogenes poses a challenge within many packing or processing environments across the entire food industry. Recognizing the importance of preventing initial contamination of whole fruit and to keep their members amongst those at the forefront of food safety, the Washington State Tree Fruit Association proactively approached United Fresh Produce Association to collaborate on a Listeria and environmental monitoring training program specific for the tree fruit industry. Though the focus is on tree fruit within the pacific northwest (apples, pears, and cherries), this training document is applicable to a variety of tree fruit in any region.


Considerations for Fresh Produce Dry-pack Environmental Monitoring Programs (EMPs)

We all know that Listeria spp. can thrive in the presence of moisture in its environment, but what about when your operation is dry? Is Listeria spp. still a concern? Should produce operations be sampling their operations for Salmonella instead? This document helps address some common questions related to environmental monitoring programs in wet vs. dry environments.


Listeria Webinars

Listeria: How to Tell if it’s Transient (Recorded 8/18/20) 

Resident and transient strains of Listeria monocytogenes can be difficult to identify. This webinar will discuss how to differentiate between the two and what to do once that determination is made. This webinar is sponsored by Ecolab. 


Building the case for Zone 1 Listeria sampling in produce operations: A review of regulatory policy and industry strategies Webinar (Recorded 10/1/19)

Unsure how food contact surface (i.e. Zone 1) testing for Listeria spp. can fit into your environmental monitoring plan without exposing your organization to regulatory risk or backlash? Join us for this 1-hr webinar to learn about the changes in regulatory thinking, conveyed via the FDA’s 2017 publication of “Draft Guidance for Industry: Control of Listeria monocytogenes in Ready-To-Eat Foods”, intended to incentivize the ‘seek and destroy’ approach to monitoring for Listeria on food contact surfaces. Still, many in the fresh produce industry (fresh-cut and packinghouses) remain understandably wary of Zone 1 testing. After covering current FDA policy related to environmental monitoring, we’ll provide detail on a new resource in development by a United Fresh workgroup: a set of guidelines and case studies that illustrate how an operation can prepare to implement Zone 1 sampling, and provide strategies for how to react in the event of a positive. After listening to this webinar, attendees should feel more confident in assessing their operation’s ability to move towards testing Zone 1 surfaces for Listeria spp. This webinar is sponsored by Ecolab. 


Managing Listeria in Fresh Produce Operations: Highlights of the updated United Fresh Guidance Document (Recorded 12/4/18)

The regulatory and public health focus on Listeria monocytogenes in fresh produce has prompted most of the industry to implement environmental monitoring programs, often referencing the 2013 industry guidance developed by United Fresh. Given the change in regulations, shift in FDA policy, and new research findings, the United Fresh Food Safety Council updated the document, adding more detail around sanitation and sanitary design, and with enhanced discussion of controversial topics including Zone 1 and finished product testing. This webinar will provide a glimpse of the rich content available in this guidance document. Part of the Food Safety Webinar Series sponsored by Ecolab.

Access the Webinar Recording

United Fresh Listeria Guidance

Guidance on Environmental Monitoring and Control of Listeria for the Fresh Produce Industry (2nd Ed.)

Listeria monocytogenes is recognized as a pathogen of concern in fresh produce handling and processing operations. This guidance is intended to be applicable to all fresh and fresh-cut produce operations, including field and field packing, packinghouses, and other produce handling operations including re-pack, value-added and transport/distribution to retail/foodservice, recognizing that vulnerability to L. monocytogenes contamination and entrenchment in equipment or a facility will depend on the type(s) and production region of the commodities handled and the nature of the handling.

All produce handling operations are encouraged to use this guidance along with other resources 1) to determine their level of vulnerability to Listeria harborage that may lead to produce contamination and 2) if vulnerable, to develop and implement an effective Listeria monitoring and control program.


Echar un Vistazo- Consejos Sobre que Hacer y no Hacer Para Controlar el Riesgo de Listeria


FDA Guidance

Sanitation and Sanitary Design


Free e-learning modules on Hygienic Design by 3-A Sanitary Standards, Inc. For more information, click here.

The following IFPA Sanitary Design document was created in 2003 for use by processing members in evaluating processing equipment for use in fresh-cut processing facilities. It informs processors about equipment features and assists them in choosing products that best meet their needs for proper sanitation, worker safety and processing efficiency.

The following three resources were created by Commercial Food Sanitation and represent the next evolution to the IFPA Sanitary Design guide. They are downloadable spreadsheets that can be used when purchasing equipment or evaluating a facility. There is no “right” or “cutoff” score; these are communication tools to understand the risks associated with certain designs so that the risks can be managed.

PSA “Name that Zone” Activity PowerPoint

In the PSA curriculum, the concept of zones is used to help growers identify areas that are food contact surfaces (Zone 1), next to food contact surfaces (Zone 2), in the processing area but not Zone 1 or 2 (Zone 3), and outside the processing area (Zone 4).  This tool helps reinforce how to identify these areas and begin to develop a sanitation program to meet regulatory expectations. The PowerPoint includes teaching and discussion notes for each one of the photos.

Other Sanitary Design Resources

Other Listeria Resources

For any questions on these resources, contact Dr. Jennifer McEntire or Dr. Emily Griep or to report broken links, contact Katie McGowan, Manager, Food Safety Programs, via email at or by phone at (202) 303-3402.