Foodborne bacteria can adapt to cleaning methods, research suggests

Food recall data in 2023​ showed that many foodstuffs were recalled due to bacterial contaminations, for example salmonella in kebabs​ and listeria in cheese​.  The EU, for example, saw the highest recall numbers since 2020, many incidents of which were linked to food contamination.

New research suggests a potential reason for high levels of infections: bacteria in factories that prepare ready-to-eat food can adapt to their environments. This means that, far from being a guarantee against infection, cleaning these preparation areas can often have little impact on the safety of the humans consuming the resulting food.

You think I’d lay down and die (from being cleaned)? No, not I, I will survive

It is well known that bacteria are not always absent from ready-to-eat food environments. Despite the best efforts of everyone involved, foodborne bacteria doesn’t always survive cleaning efforts on the factory floor, according to research by the food and health research organisation Quadram Institute and UK Health Security Agency.

Furthermore, in the ready-to-eat food category consumers won’t always heat the food before consuming it, meaning the danger is even more significant.

In order to find out how this happened, researchers sampled the floor of a ready-to-eat food factory that had recently detected Listeria monocytogenes​, in a preparation area where ingredients were kept at 4°C and a production area where food was kept at 10°C. They sampled these areas over ten weeks, both before and after cleaning, and analysed the samples to check for the levels of bacteria found.