Draft guidance addresses Listeria testing for RTE food production

Ready-to-eat (RTE) food producers were given new direction from the U.S. Food and Drug Administration (FDA) this year when its draft guidance “Control of Listeria monocytogenes in Ready-To-Eat Foods” was updated.

We’ve summarized the draft guidance before, but now we’ll go over the guideline’s approach to sampling and testing for L. mono.

Best practices

One of the biggest curveballs of the draft guidance is that it now recommends testing for L. mono in zone 1 during production runs. If a producer finds a positive result during the run, they’ve got a few matters to sort through.

The document suggests testing a few hours into the run, at least three or four, in order to allow enough time for bacteria to spread enough to be detectable.

This presents a challenge; namely, that food producers may now discover the presence of L. mono once food has already moved through the production line. How should this situation be handled? Corrective action should be taken immediately, for one.

The first time L. mono is detected, the area should be cleaned, disinfected, and retested during the next production cycle. If detected on a food contact surface, an investigation should be launched to figure out how the bacteria got there.

After the second positive result, the cleaning and disinfecting routine should be intensified. Get into the nitty gritty of equipment, and disassemble if needed to get a better clean. For food contact surfaces, the investigation should double down. In this case, if the food supports L. mono growth (or is destined for a hospital or nursing home environment), it should be put on hold and tested.

In the case of a third positive result, producers should conduct a root-cause analysis. If it’s a food contact surface for foods that support the bacteria’s growth, production should be halted and experts brought in. After more intense cleaning, the next batch of product should be held and tested until three consecutive days’ worth test negative, as well as any food contact surfaces. Any more positives, and you should stop production and consult experts for a thorough investigation as to the cause.

Where and when should we test?

The FDA suggests that at least five food contact surfaces and five non-food contact surfaces should be tested on each production line. Tests should be conducted where the greatest risk is.

Factors to consider when identifying risk:

  • Plant size and features
  • Product flow
  • Characteristics of the RTE food being produced (is it conducive to mono growth?)
  • Processing methods used
  • Results of previous tests

Testing frequency should also be determined by risk. The FDA suggests testing monthly for foods that don’t support L. mono growth, and weekly for foods that do. If the bacteria is found, testing frequency should increase.

For a more detailed summary of this part of the draft guidance, check out the Acheson Group’s review of each section.

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