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Pasteurization
The pasteurizer comprises a series of water tanks at various temperature, a series of pumps which circulate the water up to the head of the pasteurizer where it is allowed to cascade from spray heads, and a moving bed which slowly carries the bottles of beer from one end to the other through the spray of water at different temperatures.
The effect is that the bottles of beer are slowly brought up to a maximum temperature held at that temperature for a fixed period of time and then slowly cooled down again.
The amount of pasteurisation the beer receives is a function of the maximum temperature and the speed of the moving bed. Pasteurisation is measured in “pasteurisation units”(PU’s). One PU is the equivalent of holding the beer for one minute at 60°C. The number of PU’s can be increased by either increasing the temperature or by increasing the time the beer is held at that temperature. Ideally the lower the temperature the less the adverse flavour effects on the beer. However, there is a minimum temperature below which there would be no pasteurising effect no matter how long the beer was held.
Ideally the bottles of beer will take about one hour to go through the pasteurizer being held in the middle section at a temperature of 60°C for twenty minutes. This equates to 20 PU’s.
