Technical guidance: How are spirits produced?
The craft of distilling alcohol is believed to have originated in the Middle East in the 11th century, reaching Ireland by the 12th century and Scotland by the 15th. The methods employed then are still, in essence, used today, and comprise:
- the preparation of a solution containing dissolved sugars from fruit or cereals;
- the conversion of the sugars into weak alcohol by fermentation with yeast; and
- the heating of the weak alcohol solution in a pot or columns to extract the alcohol vapour and subsequently condensing the vapour into a liquid.
Spirits can also be produced synthetically by catalytic conversion (cracking) of ethylene gas, a by product from the petrochemical industry. The spirits, commonly known asindustrial ethanol, produced by this method are no less safe to drink thantraditionally-distilled spirits, but the EU only permits the use of cereal and fruit based spirits for human consumption. As a result the use of synthetic ethanol is restricted ton on drinkable uses.
Other processes used to produce spirits include:
- freezing a fermented alcohol solution to obtain a rough, comparatively weak spirit from the frozen residue;
- reverse osmosis which involves ‘sieving’ alcohol molecules through a membrane to segregate the ethanol from other components (mainly water); and
- spinning cone / falling film evaporators, which are variants of traditional stills. These devices evaporate a continuous stream of feedstock against a spinning cone under pressure.
Reverse osmosis and evaporators are used mainly to extract alcohol from beer, wine andcider to produce low or alcohol-free beverages.