Pasteurization of bread is understood to be the packaging of the whole loaf or sliced loaf and the subsequent re-heating up to a core temperature of 78° C. Corresponding heat-resistant packaging materials are necessary for wrapping. In the case of the packaging, this is, as a rule, the sales packaging. The packaging should be tight around the bread and has to have an airtight seal to prevent mould fungi spores finding access during cooling.
In small and medium-sized bakeries, rack ovens are suitable for the pasteurization process, as, due to the convection, a rapid transfer of heat takes place. Temperatures of approx. 120° C are normally sufficient to reach the core temperature of 78° C after around
75 minutes. The core temperature has to be maintained for at least 10 minutes.
For a rapid heat transfer, the highest setting of the air circulation should be programmed. In the case of pasteurization in deck ovens, the temperature of the oven should be set at around 130 – 140° C, as the heat transfer takes correspondingly longer with a static heat. This also depends on the type of oven used and should be checked by in-company readings.
In plant bakery companies, special pasteurization ovens are used which are run with slight over-pressure in the baking chamber, whereby the pasteurization time is shortened. These ovens frequently have a core temperature sensor. The length of the baking program depends on achieving the necessary core temperature in this case.
As soon as the packages with the sliced bread have left the oven, visible condensation appears on the inside of the packaging material due to the difference in temperature. This can sometimes be so high that droplets are formed. This is why cooling should take place slowly to keep the condensation as low as possible. The condensate formed is partly taken up by the bread during cooling. Darker bread, such as wholemeal rye bread or coarse grain bread, is better suited for pasteurization than light-coloured wheat bread, as, in the case of dark types of bread, changes in colour or texture, which can occur as the result of the pasteurization process, are noticed only slightly or to a very low extent. The pasteurization time is nowadays reduced to a minimum and used as an addition to other mould protection measures.