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Making Scotch whisky
For a drink capable of such complex flavours, it's surprising to realise that Scotch whisky is made from only three ingredients: malted barley, water and yeast. The processes by which these are turned into uisge beatha have been refined down through the centuries but apart from the scale and complexity of the hardware, in essence they have remained the same for much of this time.
There are two basic whisky types distilled in Scotland: malt whisky and grain whisky and each involves a different production process.
Malt Whisky
There are five basic stages in the production of malt whisky:
- malting
- mashing
- fermentation
- distillation
- maturation
Grain Whisky
Grain whisky is produced by a Coffey or Patent Still and uses wheat, maize or other cereals, rather than barley, in its production processes.
Malting
The process begins with the malting of the barley. The barley is first soaked in large tanks of water known as barley steeps for up to four days before being spread out on the floor of the malting house to germinate. Over the next 12 days or so, the barley is turned over, either by hand in the traditional manner or more likely nowadays by machine, to allow it to sprout, causing the starch in the grain to be converted to the sugars that wlll be essential in the later stages of production.
Germination has to be controlled however and the process is halted by drying the barley in a malt kiln fired with peat, a natural fuel cut from the Scottish moors. The peat smoke is allowed to filter through the drying barley to different degrees by each distillery and can often be tasted in the final whisky itself. The kilns traditionally had pagoda-shaped chimnies and these have become the characteristic mark of every distillery.
Mashing
The malted barley is now roughly ground and the resulting grist is mixed and agitated with several flushes of hot water in a large cylindrical vat called the mash tun . In the mash tun, the sugars in the barley grist dissolve to produce a hot, sweet, non alcoholic liquid , the wort .
The draff , the spent grist left in the bottom of the mash tun once the wort has been drawn off, is recycled as fertiliser for use on local farms.
Fermentation
After mashing, the wort is cooled from around 63°C to about 20°C to allow the addition of the yeast which takes place in large wooden or metal vats called washbacks . Fermentation now begins and the sugary wort is converted into a low-strength alcohol called wash . At the outset, the wash is very similar in strength to beer (around 7% ABV) but by the end of the 50-hour fermentation, this has increased to around 24%.
The wash is now ready for distilling.
Distillation
Scotch whisky is usually distilled twice (the exception being Auchentoshen, which is given an extra run through the still) in the distinctive swan-necked copper pot stills.
The wash is first run through the wash still which removes the yeast from it. Since it has a lower boiling point than water, the alcohol in the wash evaporates first and rises as steam through the narrow neck of the still to the worm , a condensing coil to produce a distillate called low wine .
The low wines are then passed through the spirit still to repeat the process. This raises the alcohol content of the resulting liquid to between 70% and 80% ABV - a very powerful potation indeed!
To the uninitiated, all stills appear to be the same. In fact, the precise shape of the still is a crucial part of the distillation process and can have a decisive impact upon the character of the whisky it produces. For example, stills with short necks produce whiskies with heavier oils which give more intense flavours, whereas long-or high-necked stills produce less-intense whiskies because of the lighter oils produced during distillation.
From the second distillation, the crystal-clear spirit is run off via the glass-fronted spirit safe . This 'safe' is heavily padlocked by the Customs & Excise to prevent any possibility of the distillery syphoning off the spirit to avoid paying the legal duty on it. Because the stillman is therefore unable to smell or taste it, he has to exercise all his skills and judgement to decide when to separate the middle cut of the spirit (which contains the best-quality alcohol needed for maturation) from the foreshots (the poisonous first part of the distillate) and the feints or aftershots which contain lower grade alcohols.
Maturation
The final stage in the process is allowing the new whisky to 'mature' in wooden casks for several years to allow it to develop the desired colouring and flavour characteristics.
The choice and quality of these casks play a crucial role in the character of the final product. New casks are never used since these have nothing to impart to the new spirit. Instead, casks which have previously been filled with fino, amontillado or oloroso sherry or bourbon are preferred, particularly when made of oak. This is because quantities of the original contents will have seeped into the cask wood, which in turn imparts elements of their flavour to the new whisky as it matures in the dark of the store room.
Casks are a valuable commodity to whisky producers since the demand for them far outstrips the supply. Consequently, whisky-filled casks have to be recycled for subsequent distillations but of course, there are less of the original-fill flavours available with re-use. Some producers, such as The Macallan, have tried to get round this problem by buying their own Spanish sherry bodega in Jerez to guarantee supplies of good quality first-fill sherry casks, something which comes across very strongly in their whisky.
Grain whisky production
The early stages of grain whisky production are very similar to those involved in malt whisky. The major differences are that wheat, maize or other cereals are used, rather than malted barley, and that the distillation part of the process uses a completely different type of still, the Coffey or Patent still .
The Coffey still comprises two large cylindrical columns linked by a complex network of pipes. The wash initially flows into and through the rectifier column in a continuous run of pipes which snake up through its entire height. As it does so, it is steam-heated. It then passes into the analyser column where it encounters further steam blasts and a condenser coil. The impure alcohols in the first and last part of the distillate can be fed back into the rectifier for redistillation while the spirit which reaches the spirit safe is generally very pure.
Grain spirit matures faster than malt, and is less prone to variation. Once it reaches its minimum 'legal' age of three years, the vast bulk of grain whisky produced is sent for use in blending with only a few brands being made commercially available.
Provided by www.visitscotland.com
