Manufacturers of fruit preparations usually use steel containers to store batches of their product. After each emptying process, these must be sterilized before they are refilled. Despite strict cleaning requirements, the risk of mold growth still remains. Mold is usually detected by microbiological methods, which provide results only after 24 to 48 hours due to the long incubation period and slow growth of the causative agents. Regular analysis for ongoing mold growth is important. However, this is not easy with methods that take so long.