Principles of pasteurisation

Pasteurisation is not full sterilisation it is what has been termed practical sterility (European Brewery Convention, 1995). Microorganisms that are able to grow in beer need to be killed in order to achieve stability, but the heat treatment does not have to be to such a level to kill heat resistant spore forming bacteria, as they are unable to grow in beer. Applying the minimal amount of heat necessary to achieve stability ensures that both the effect on flavour and energy use is minimised. Pasteurisation will not, however, solve problems in beer quality that poor hygiene can cause before pasteurisation is carried out  

The temperature applied during pasteurisation and the length of time it is applied for are of critical importance in pasteurisation, as is which microorganisms are present in the beer and the quantity in which they are found. 

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