FDA Listeria Draft Guidance for Ready-to-Eat Foods: Part 1

FDA Listeria Draft Guidance for Ready-to-Eat Foods: Part 1 is an outline of essential information on the Listeria draft guidance, answering who, what, when, where, why and how questions. The guidance is written for companies manufacturing ready-to-eat (RTE) food and ingredients. As a guidance document the language is different from a rule where companies are required to comply. In general, an FDA guidance document does not require compliance, is written to help industry interpret rules, and explains FDA’s current thinking on a topic. The FDA Listeria Draft Guidance is different. In this author’s opinion, the guidance carries the full weight of a rule and will be enforced as such by FDA. If your company manufactures a RTE food, your President or company owner must be fully informed on the contents of the guidance. This paragraph answers why.

Who must test for Listeria?
All food companies making RTE foods under the jurisdiction of the federal Food and Drug Administration (FDA).

What must be tested for Listeria?
The company will identify food contact surfaces (FCS) and non-food contact surfaces (NFCS) as appropriate to the design of individual facilities. Finished product testing is discussed in the guidance and is recommended.

    We recommend that you establish and implement a written procedure for the periodic collection of samples of your RTE food product, and for testing those samples for the presence of L. monocytogenes. See page 52.

What sterile supplies are needed?
The best method to sample a surface uses a premoistened, sterile sponge on a stick. My personal favorite comes from World Bioproducts. In addition to sponges, companies can use any sterile tool including Q-tip type swabs, tongue depressors to collect solids, scoops, dippers, pipets, bottles or bags. If you are concerned about contamination during sampling, have sterile gloves available for your technicians and intensify training. Finished product may be shipped in final packaging, or, if the finished product is large, a trained technician can obtain a portion aseptically to ship.

What lab method for Listeria is used?
When samples are sent to your contract lab, you specify for the testing of Listeria genus or Listeria monocytogenes. You can specify a one- or two-step enrichment. There are pros and cons for every method and its application, but you are expected to use a standard method which has been validated when testing for Listeria. Indicator tests which do not directly test for Listeria are useful for zone 1 and 2 samples; my favorite is an indicator test called HQA.

When are FCS sampled?
Warning! Warning! You are not going to like the answer. FDA wants food companies to sample FCS after three hours into production. The reasoning here is that microbial niches will have shook free and the conditions are representative of normal operations. Be very careful if following this FDA recommendation.

When are NFCS sampled?
NFCS can be sampled at any time provided food is not affected in the process of sampling and a positive Listeria test would not be associated with the product. When NFCS are tested as part of pre-op, this is a verification activity for a sanitation program.

Where are samples taken?
FCS and NFCS samples must be taken from every production line and from any area in the facility beyond production lines.

How many samples are taken?
A minimum of five samples from FCS (Zone 1) must be taken from every line every week. A minimum of five samples from NFCS must be taken. Imagine you have four lines in each room. You will take a minimum of five FCS samples from every line, for a total of 20 samples. Know that FDA is very conservative on their definition of FCS. For example, a control panel can be a FCS, if the technician who touches the panel in turn touches the production line or product. The same is true of overhead structures like pipes where condensate or powder could fall on to the product. How you interpret the minimum of five NFCS samples is up to you and dependent on the variables in that room. In general, FDA wants to see more samples from Zones 1 and 2 than from Zones 3 and 4.

What is the frequency of testing for Listeria?
Designing the sampling plan for Listeria testing is an art and a science and determines the cost to the company. Here are examples provided in the FDA Listeria Draft Guidance. See pp. 37-38. Pay attention to the wording on frequency:

    An example of how to specify the frequency of sample collection in a written environmental monitoring plan for FCSs in an establishment producing an RTE food that supports growth of L. monocytogenes is as follows:
    • Collect environmental samples from specific FCSs on the production lines at least once every week when the plant is in operation; and
    • Test each FCS in the plant at least once each month.

    An example of how to specify the frequency of sample collection in a written environmental monitoring plan for non-FCSs in an establishment producing an RTE food that supports growth of L. monocytogenes is as follows:
    • Collect environmental samples from representative sets of non-FCSs at least once weekly for zone 2 sites, every two weeks for zone 3 sites, and monthly for zone 4 sites when the plant is in operation; and
    • Test all non-FCS sites identified in the monitoring plan at least once each quarter.

Table 4 in the guidance, pp. 34-35, is the only published FDA guidance on zone designation of which this author is aware. Please share FDA publications on zone designation with me. I would love to talk through the design of your Listeria sampling plan with you. You can reach me by signing up for Expert Services on connectfood.com.

Of course you still have questions! The ConnectFood website has free resources, and the folks at ConnectFood are here to help! Contact us.

About the Author
Kathy Knutson, Ph.D.
Kathy Knutson Food Safety Consulting
Dr. Kathy Knutson works nationwide with food manufacturers on recall investigations, problem-solving, training, and Food and Drug Administration (FDA) compliance. After being trained in 2016 as a Lead Instructor with the FDA-recognized curriculum for Preventive Controls Qualified Individuals, she delivered over 20 workshops to industry. With over 35 years in microbiology and 15 years of full-time teaching, Dr. Knutson is passionate about training and is an effective communicator at all levels in an organization. She has taught and consulted with companies on laboratory methods, interpretation of lab results, quality assurance, sanitation, environmental monitoring, Standard Operating Procedures (SOPs), Good Manufacturing Practices (GMPs), Hazard Analysis and Critical Control Points (HACCP) and the FDA’s Food Safety Modernization Act (FSMA). As a life-long learner, Dr. Knutson is trained in prevention of intentional adulteration, a topic on the horizon for the food industry. Dr. Knutson is a contributing author at CannabisIndustryJournal.com. Dr. Knutson writes a food safety blog and contributes expert services to manufacturers through connectfood.com, an online site for writing HACCP and food safety plans. When Dr. Knutson is not traveling, she works from home in Green Bay, Wisconsin, where she lives with her husband, two sons, and an adorable Bernedoodle. Learn more about her at https://www.linkedin.com/in/kathyknutsonphd