The limits apply based on whether growth of L. monocytogenes will or will not occur in the RTE food:
- for RTE foods in which growth of L. monocytogenes will not occur, the limit is less than 100cfu/g.
- for RTE foods in which growth of L. monocytogenes will occur, L. monocytogenes must be undetectable in 25g.
This approach is risk-based and informed by scientific knowledge on factors affecting the risk of acquiring listeriosis illness. It is consistent with international approaches, including Codex guidelines and recognises that L. monocytogenes can grow to high numbers in some foods and should not be present at detectable levels if the food is to be kept safe. In other foods, where we know the pathogen cannot grow, there is a possibility for occasional low-level detections that will not affect the safety of the food.
Read our Guidance on the application of microbiological criteria for Listeria monocytogenes in RTE food. It includes a decision tree to help decide what limit applies.