Environmental monitoring

It’s important to recognize that a clean environmental monitoring test result doesn’t confirm that your food is safe, rather it verifies that your cleaning processes are effective.

Sanitation verification by ATP meter or aerobic plate count (APC) answers the question: Did I do what I said I was going to do? Verification is not the same thing as environmental monitoring. Environmental monitoring (EM) answers the question: Is what I said I was going to do in my SSOP good enough?

A strong EM program can also help limit the scope of a potential recall, or even prevent a recall by providing evidence of an effective sanitation program and corrective actions, when necessary.

Do not implement an EM program until after you have thought through and documented a corrective action process, should it become necessary.

The most likely reason that an EM program never detects Listeria species is because “the sampling and/or testing procedures are not rigorous or sensitive enough.” Listeria monocytogenes (LM) is the pathogen of greatest concern for most fruit packing facilities, and it is also a natural inhabitant of the growing environment, so it is likely to be present at some level at some time in all packing facilities.

“Being so close to product contact surfaces, they [Zone 2 surfaces] are more likely than Zone 3 to accumulate moisture and nutrients and, if Listeria become entrenched, provide a shorter distance to product contact surfaces. Detection of Listeria on a Zone 2 surface should be taken seriously; since Zone 2 is not product contact, any Listeria detected are less likely to be transients from incoming produce and may be more likely coming from the production environment itself.”

Ten sites and five samples from among those ten sites every two weeks for Listeria species should be considered the minimum for even the smallest of operations. In other words, identify a total of ten sampling sites and then sample five of those sites one week, followed by sampling the other five sites two weeks later; continue to alternate sites in that way every two weeks throughout the season. Focus on Zone 2 and wherever moisture and exposed product are present together, for instance, washer-waxer framework. Make sure highest-risk areas are represented in each set of biweekly samples. Sample a similar number of food contact surface sites every two weeks for APC or Enterobacteriaceae (EB), depending on risk assessment.

Facilities with hydrocoolers and cold storages include additional challenges involving LM due to the combination of moisture and traffic. While LM on a wet cold-room floor may have little chance of contaminating packaged product directly, one must account for the fact that forklift traffic and high-risk sanitation practices such as the use of pressure washers and compressed air can spread LM throughout a facility.

“Quoted content” above is from Strategies for Listeria Control in Tree Fruit Packing Houses, First Edition, United Fresh Produce Association, 2018.

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