A sticky layer of bacteria that attaches to surfaces such as equipment and drains, protecting the microbes from cleaning and sanitising.
The bacteria produce a slimy protective matrix that sticks them firmly to the surface and blocks sanitisers from reaching and killing the cells, so a quick wipe or spray on its own will not remove it.
Moist spots that are not cleaned thoroughly are the usual sites, including drains, sink undersides, taps, hoses, ice machines, and scratched or worn food-contact surfaces on equipment.
Yes. A biofilm can be invisible to the eye, which is why a surface may appear clean and dry yet still carry live bacteria that can contaminate food.
Clean first with detergent and physical scrubbing to break up the matrix, rinse, then apply sanitiser at the right strength and contact time. Badly scratched surfaces that cannot be sanitised should be replaced.
Listeria monocytogenes is a common concern because it can survive in cool, damp environments and establish persistent biofilms in ready-to-eat food processing areas.