The most important raw material used in the production of spirits and liqueurs is water. Water is used throughout the spirit production process, including fermentation and distillation, and is finally added to reduce the spirit to bottling strength. In a standard bottle of spirit with a 40% ABV (Alcohol By Volume) or 80 proof and the other 60% is water.
The other raw materials are starch or fermentable sugars. These are recognized as grains (barley, wheat, corn, rye and other cereals) used to make vodka, gin and whiskies; plants (agave, sugar cane, sugar beet and potatoes) used to make tequila, rum and potato vodkas; and fruits (grapes, apples, pears, cherries, apricots, plums, berry fruits and other soft tree fruits) used to make brandies/eau de vie.
Ethanol is produced by fermentation. In order to produce ethanol starch must first be converted into sugars. Once the raw materials have been converted into sugars, water and yeast are then added and the liquid is left to ferment from 40 hours up to a week or more.
Adding yeast begins the fermentation process and is the magic ingredient in the production of alcohol. As the yeast feeds on the sugars and converts them into alcohol gas is produced in the form of carbon dioxide. The fermentation process enhances the natural flavour of the starch, the resulting liquid is known as the ‘wash or beer’, and will generally have an alcoholic strength of between 7 and 11%.
The wash is then distilled in either a copper pot or column stills or in some cases in both, yielding a spirit with an ABV of between 45 and 96%. The boiling point of alcohol is 78.3°C and the alcohol rises in a vapour form. This vapour is then cooled and collected by a condenser (cooler) and as it cools it returns to a liquid form – this is the first distillation.
Pot still distillation is a traditional method that produced heavier, more flavour some spirits. Alembic or pot stills work in a similar way to a traditional kettle. The alcoholic liquid is put in the pot, which is then sealed. Heat is applied to the base and as the mixture inside heats up, the alcohol boils and turns to vapor. The vapor continues to get hotter until it is light enough to reach the very top of the still, which is cooler due to a jacket of cold water that cools the vapor to return it to liquid form. The liquid then enters a spirit safe where it is collected. The shape of the still can heavily influence the characters of the alcohol it produces.
The column still
The column still, also known as the continuous still, is more efficient in mass producing a lighter spirit and is far easier to control. Every time a pot still is used, the residue must be emptied and the still cleaned before moving on to the next batch. With the column still, the alcoholic liquid is pumped in via the top and steam is pumped in through the bottom. When they meet, the alcohol starts to boil and rises back up the column. As the alcohol becomes lighter and purer, the column can be set to capture the alcohol at any specific point, from 13% up to 96.4%.
Filtration has been used since the earliest production of alcohol and is used to remove unwanted particles or sediment and is the easiest way to improve the quality of a spirit. There are various filters used, such as quartz sand, flint, diamond dust, cloth and more commonly activated charcoal. Depending on the spirit and distillery, filtration can be used at various stages: as the water is added, before the spirit is aged and before bottling. In modern spirit production filtration is primarily used to ensure that impurities are removed from the spirit and to enhance clarity and crispness but filtration as such has little effect on the flavour of the spirit.
Ageing or maturation is used for dark spirits such as rums, tequilas, whiskies and brandies. Vodka and gin are un-aged spirits. When the spirit leaves the still it is generally clear and the spirit is placed in oak barrels, or casks, and ageing then takes place. The maturation process affects the spirit’s final aroma and taste. In many cases the majority of an aged spirit’s flavour and colour is taken from the oak barrels and is generally associated to the length of time a spirit has been in a barrel. Some products, such as tequilas, are aged for up to sixty days whereas some whiskies and cognacs can be aged for decades.
Other factors that affect maturation are the type of oak, temperature, humidity, time and location. The casks expand and contract as a result of temperature and climate change over time, drawing the spirit into the wood in the cask and forcing it back out releasing tannins, vanillin’s and colour. Climate can also vary dramatically from the seasonal highlands of Scotland (whiskies) to the humidity of the Caribbean (rum) and Mexico (tequila).
The size of the barrel and how many times it has been used can also impact on the final product. Spirits aged in a small barrel have more contact with the surface of the wood and therefore gain wood characters more quickly than spirits aged in a larger barrel.
Blending, also known as vatting, is a fine art. It is the job of the master blender to ensure that the final product is consistent, taking into consideration the complexity of woods and finishes of a particular range of casks. A blend can be taken from as little as a dozen casks up to fifty or more of varying ages. They are then left to marry in large vats from as little as two to three days up to a year or more. Blending is by no means dilution and the aim of the master blender is to produce a blend that brings out the best qualities of each of its constituent parts. The blends are then usually returned to the cask and left to marry for a period of months, before bottling.
Before the spirit is bottled, the spirit needs to be reduced to the usual bottling strength (about 40% ABV, unless the spirit is labelled cask strength), by diluting it with water. As mentioned previously water is a vital component and is integral to the taste of the final product. The spirit is then sent to the bottling line where it is pumped into glass bottles. Glass is non-reactive, other receptacles, such as plastic, would cause a chemical change in the beverage. The bottling procedure is highly mechanized as the bottles are cleaned, filled, capped, sealed, labelled and loaded into boxes ready for distribution. This can be done at rates as high as 400 or more bottles per minute.