Stage 5
Spirits & Liquors
Distillation Process
Distillation is an ancient process used to concentrate a particular component of a liquid, in this case alcohol, through a method of separation by boiling and condensing. For the production of spirits, the aim of the distillation is to increase the alcohol content of the liquid.
Method of Distillation
The process of distillation involves warming the alcoholic liquid so that the ethanol (drinkable alcohol), which boils at a lower temperature than water, can be boiled off, collected, cooled and then condensed back into a higher strength alcoholic drink. Through the distillation process, most of the water contained in fermented alcoholic drinks is left behind. The unfermented sugars, colour compounds and solids are also left.
Main types of still used
Distillation is carried out in a still and although there are many different types of still, they all follow either the Pot Still or Column Still pattern.
Pot Stills
The pot still is the most simple and oldest form of still. The pot is usually made of copper and the base alcoholic liquid is placed in the pot while it is heated. Above the pot is the still head and then a neck (swan's neck) which collects the vapours of the alcohol as they are boiled off. These vapours then flow through the coil in the condenser, which contains cold water to condense them back into liquid.
The first components to boil off are called the 'heads', or foreshots. The heads are also the most volatile components as they contain concentrated poisons, including methanol. The 'hearts', or spirit, are the next component to boil off and these contain the highest proportion of ethanol and the lowest proportion of undesirable impurities. The final and least volatile components to boil off are the 'tails', or feints. The heads and tails are not used in the final spirit but they are returned to the pot to be redistilled with the next batch as they still contain a certain amount of desirable ethanol.
Pot distillation is actually a relatively inefficient method as two or more distillations are required in order to produce a spirit of sufficient strength. Even with multiple distillations, the final spirit is far from pure.
The photograph and diagram show a Cognac pot still and although pot stills used for the production of spirits vary in shape and size, they all follow the same processes of evaporation and condensation.
Column Stills
The column, or continuous still was invented in the nineteenth century and solves many of the problems, which occur with distillation in a pot still.
A single distillation in a column still can produce a liquid, which is almost pure ethanol. It can also be run continuously and effectively as it is not a batch process. There are many variations of design of column still, all of which are quite complex. Some column stills are designed to produce a lower strength spirit with more impurities and, consequently, more flavour too.
Continuous Still
Main ingredients used
The main ingredient of a spirit is of course, the base material which is destined for fermentation and then distillation. Below are some examples of base materials and the spirits they can be distilled into.
| Base Material | Spirit |
|---|---|
| Wine | Brandy; e.g. Cognac, Armagnac, Brandy de Jerez |
| Grape skins or residue left over from fermentation | Grappa, Marc |
| Fermented Apples or Pears | Calvados |
| Pears, Cherries, Plums and other fruits | Eaux de Vie |
| Grain e.g. barley, maize and rye | Whisky/Whiskey |
| Molasses | Rum |
| Any fermentable material e.g. potato, grain, grape | Vodka and other neutral spirits such as the base spirit used in the production of Gin |
Spirit, Strength and Characteristic
On the whole, spirits with a lighter character and flavour will tend to be purer and higher in strength. After being reduced, or watered down, to the standard bottling strength of about 40% abv, these spirits are ready for immediate consumption and do not necessarily need to undergo any maturation.
On the other hand, spirits with a lower strength immediately after distilling will contain more impurities and the flavour character of the base material will be much more evident. However, this does also cause the spirit to be harsher so these spirits will require either a period of maturation in oak or filtering with charcoal to soften them.
An important point to remember is that all spirits are water-white immediately after distillation and any colour in the final spirit comes from colourings (e.g. caramel) or from the effects of oak ageing.
Likewise, all spirits are bone dry after distillation (sugar is non-volatile) so any sweetness in the final spirit will have been added (e.g. dark rum), has appeared as a consequence of the breakdown of oak into sugars during the ageing process (e.g. Bourbon) or just comes from the slightly sweet flavour which alcohol has.
The tannins and acids which are present in fermented drinks are also non-volatile so will not be present in the spirit, unless the spirit has absorbed tannin from the oak barrels during the maturation process.
See the Key Facts for Distillation.