Abstract: The invention relates to a device for the rapid freezing of the surface or for the complete freezing of starting substances, in particular of food or pharmaceuticals, said device comprising a treatment zone (B), through which a cryogenic liquefied gas flows as a coolant, said gas thereby freezing at least the surfaces of the starting substances and thereby causing relative movements between the starting substances, which are immersed in the coolant. The treatment zone (B) is made up of modules (M1, M2, M3, M4) and the length thereof can be changed by adding or removing one or a plurality of modules.