The biofilm on “impermeable” material
A smooth and impermeable material apparently is not the “panacea” of hygiene, especially in reusable containers, for wear and tear with some bacteria tend to adhere to hard surfaces, multiply and produce extracellular polymeric substances, called "biofilm"
Bacteria trapped in the "biofilm" can be well protected from active compounds used for cleaning, especially in the presence of fatty deposits. The pathogens are of particular concern, since the biofilm may facilitate its spread on surfaces and their transfer to the product packaging.
Several studies have shown that these cells appear to be more resistant to disinfectants (Schwach & Zottola, 1984, Frank and Koffi, 1990; Wirtanen and Mattila-Sandholm, 1992a, b).