Following the baking process, the baked goods are practically sterile when they leave the oven. If a contamination by mould fungi spores is successfully prevented during cooling, cutting and wrapping, then the use of preservatives or pasteurization can largely be dispensed
with.
This is made possible by a clean room which is separated hermetically from other rooms and which is located directly behind the exit of the oven. Cooling, cutting and wrapping the baked goods take place in this room. Extensively filtered air is blown into the room with as little turbulence as possible and a slight over-pressure created to prevent mould fungi spores entering via the air from outside the clean room.
According to ISO 14644-1, clean rooms are divided into categories 1 – 9, whereby category 1 has the highest requirements. The categories are based on a maximum particle concentration permitted in the room. Clean rooms for bakery companies should comply with category 8 at least (cf. Meißner 2012).
As a result of the high hygiene prerequisites necessary and the investment costs, clean rooms are primarily used by large bakery companies. They are then part of a production line with which only one category of products is manufactured. Toast bread, sandwich bread, pre-packed sliced bread and pre-baked goods are nowadays packaged in plant bakeries on a large scale with the help of clean room technology.