Distillation in beer production
Essentially there are two main ways of brewing a beer with low levels of alcohol. You can limit fermentation so that the yeast is unable to produce alcohol or you can remove the alcohol from a normally brewed beer.
There are a number of methods that can be employed to remove alcohol from beer and these include distillation, evaporation, reverse osmosis and dialysis. Distillation relies on the fact that alcohol has a lower boiling point than water. Therefore when beer is heated the alcohol is distilled off and leaves behind de-alcoholised beer. Unfortunately many of the flavour compounds in beer also have low boiling points also will be lost along with the alcohol. This requires some flavour adjustment to take place after distillation has occurred.
The distillation of beer can be carried out at either ambient pressure or under vacuum. Unfortunately the prolonged heating involved in ambient pressure distillation can have a negative impact on beer flavour and is rarely used nowadays.
However, if you carry out the distillation under vacuum then lower temperatures can be employed thereby reducing the impact on flavour. This is because the temperature that alcohol boils at decreases with decreasing pressure. For example water will boil at a lower temperature in the low pressure environment that you would encounter up a mountain but will boil at a much higher temperature when stuck in a high pressure cooker. Therefore vacuum distillation enables a lower distillation temperature to be employed to remove the alcohol from beer and so is preferred.
The fermented beer is warmed and then pumped into a vacuum chamber and condensed, a process that separates the alcohol from the body of the beer and reduces the beer to a thick concentrate. The concentrate is then cooled and water and CO2 are added to produce a carbonated malt beverage.
Ambient Pressure Distillation
Pressure : atmospheric (approx 100 kPa) Temperature: 78.3 °C (173.5 °F) (this temperature will vary slightly with altitude “barometric pressure”)
To produce beer of approx 0.5% alc v/v Typical Pressure: 6-10 kPa Typical Temperature: 42-44°C (107.6-111.2°F)