The heat treatment of beer to kill microorganisms and provide stability to brewery processed beer. Flash pasteurisation is commonly conducted by passing beer through a heat exchanger heated with steam. The rapid flow of the beer ensures a limited time of contact of around 30 seconds at a temperature of 73oC and minimises degradative effects on the beer. Despite this pasteurised beer often tastes oxidised and aged due to the oxidisation of components at the high temperatures. Pasteurisation is measured in pasteurising units (PU) which are defined as the effect on microorganisms of holding the beer at 60oC for one minute.