Scottish single malt whisky comes in four varieties, based on where it is distilled. The four whisky regions of Scotland are the Highlands, the Lowlands, Islay, and Speyside. Each region has a distinctive nose and flavor, and each individual whisky adds its own elements, based on the equipment, the ingredients, the location of the distillery, and the production process.
Whisky Production
The production of whisky has six main steps. First, the barley used must be malted, after which it is mashed, fermented, distilled twice, and finally matured.
Malting the Barley
The barley used in Scottish single malt whisky must first be germinated. It is soaked in tanks of water for several days before being spread out on the floor of the malting house. As the barley germinates, it produces heat, and so it must be turned over regularly to prevent too much heat from building up. This is usually done by throwing it into the air with wooden shovels. When the barley has germinated enough (anywhere from two days to a week), it is now called green mash. It is put in kilns, where it is dried over peat fires, stopping the germination process. The temperatures are kept low, to prevent the breakdown of enzymes produced during germination, which will convert the starch in the green mash to sugar.
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After the barley has completely dried out, it is ground finely, and mixed with hot water in a mash tun. The water is added in stages, gradually getting hotter. After the starch in the barley has dissolved into the hot water, and the used grain is strained out, the liquid is known as wort.
Fermentation
After mashing, the wort is cooled and moved into a washback, a vessel used to hold the wort while it ferments. Yeast is added, and the fermentation process begins. The yeast break down the sugars in the wort, changing them into alcohol. After about two days, the fermented liquid, now called wash, is six to eight percent alcohol by volume, and is ready for distillation.
Primary Distillation
The wash is moved into pot stills, made of copper, for distillation. Each still is shaped slightly differently, and so distills the wash differently. For this reason, distilleries avoid changing the shape of their still, to preserve the unique flavor of their whisky. The temperature in the still is raised to just below the boiling point of water. This allows the alcohol and other chemicals in the wash to vaporize. As the vapors travel out of the still, they are condensed, using a water cooled copper coil.
Secondary Distillation
The distillate, known as low wines, is then passed into a spirit still for the final distillation. This step is much more demanding, as the stillman has to avoid collecting all but the "middle cut". The "foreshots," volatile compounds which evaporate before the alcohol, and "feints," oily compounds that come after, need to be separated from the middle cut. These are returned to the spirit still to be redistilled with the next run. The result of the secondary distillation is a colorless liquid about 68% alcohol by volume.
Maturation
After being reduced to 63% alcohol by volume by the addition of pure Scottish spring water, the distillate is put in casks for maturation. The previous contents of the casks, commonly sherry, bourbon, or whisky, will impart the whisky with most of its flavor. To be called Scotch whisky, the whisky must age a minimum of three years in the cask, in Scotland, but most whiskies are aged more, often twelve to twenty-five years. After it has aged, the whisky is bottled and sold.
Whisky Regions
Lowland
Most people feel that Lowland malts are the lightest of the whisky regions, with a sweet, less peaty taste.
There are relatively few Lowland distilleries.
Highland
The Highland malts are very mellow, with a sweet, sometimes smoky or peaty taste.
The Highlands distilleries account for about one third of the distilleries in Scotland.
Islay
The Islay malts have the strongest flavor, very peaty and smoky.
Speyside
The Speyside malts account for about half the whisky produced in Scotland, even though the Speyside region is very small in terms of area. They have a very sweet, almost fruity taste that sometimes has hints of honey.
Foriegn Single Malts
In addition to the single malt whiskys produced in Scotland, which are classified as Single Malt Scotch, there are several other single malt whiskys produced in other countries. As mentioned above, these are not true 'Scotch', as they are not aged in Scotland, but are often marketed as such.
Northern Ireland
Japan 「日本」
Wales (Cymru)
sources for this node
The Scotch Whisky Association. http://www.scotch-whisky.org.uk/ The Scotch Whisky Association 07/23/02
Water of Life. http://www.whisky-heritage.co.uk/information/wateroflife.html. The Scotch Whisky Heritage Society. 07/23/02
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