Single Malt Scotch

Single malt offers the greatest variation and depth of flavour of all spirits, despite being made from just barley, yeast and water. A single malt whisky must be produced at a single distillery, distilled from malted barley and water. The mash must be processed at the distillery and converted into a fermentable substrate using only endogenous enzyme systems and fermented only with the addition of yeast. The spirit must be aged for at least three years and one day, and have nothing added to it.

Distillation of whisky has been performed in Scotland for centuries. The earliest written record of whisky production in Scotland from malted barley is an entry on the 1494 Exchequer Rolls, which reads “Eight bolls of malt to Friar John Cor, by order of the King, wherewith to make aqua vitae.” In the following centuries, the various governments of Scotland began taxing the production of whisky, to the point that most of the spirit was produced illegally. However, in 1823, Parliament passed an act making commercial distillation much more profitable, while imposing punishments on landowners when unlicensed distilleries were found on their properties. George Smith was the first person to take out a licence for a distillery under the new law, founding the Glenlivet Distillery in 1824. In the 1830s, Aeneas Coffey refined a design originally created by Robert Stein for a continuous still which produced whisky much more efficiently than the traditional pot stills, but with much less flavour. Quickly, merchants began blending the malt whisky with the grain whisky distilled in the continuous stills, making the first blended Scotch whisky. The blended Scotch proved quite successful, less expensive to produce than malt with more flavour and character than grain. The combination allowed the single malt producers to expand their operations as the blended whisky was more popular on the international market. As of 2004, over 90% of the Single Malt Scotch produced is used to make blended Scotch.

All Single Malt Scotch goes through a similar batch production process, as outlined below. At bottling time various batches are mixed together or vatted to achieve consistent flavours from one bottling run to the next. Even better at creating consistent expressions than others. Also, distillers (both independent and official) may choose to change expressions in any way to attract more or a different kind of buyer. On the other hand, distillers might also choose to make batch variation into an asset.

WATER - is used in all phases of the production of whisky. It is added to the barley to promote germination, used for mixing with ground barley grist to create a mash and to dilute most whisky before maturation and once again before bottling. Most distilleries use different water sources in the various steps. Since huge amounts of water are used during the process of whisky production, water supplies are a key factor for the location of any distillery.

MALTING - The barley used to make the whisky is “malted” by soaking the grain in water for 2–3 days and then allowing it to germinate to produce the necessary enzymes required to convert starch into fermentable sugars. Traditionally each distillery had its own malting floor where the germinating malt to exact specifications, but the “pagoda roof” (many now false) which ventilated the malting floor can be seen at nearly every distillery. The germination is halted (by heating) after 3–5 days, before the starch begins to be converted into the fermentable sugars. The method for drying the germinated barley is by heating it with hot air produced by an oil, coal or even electric heat source. In most cases, some level of peat smoke is introduced to the kiln to add phenols, a smoky aroma and flavour to the whisky. Some of the more intensely smoky malts from Islay have phenol levels between 25 and 50 parts per million (ppm). More subtle malts can have phenol levels of around 2–3 ppm.

MASHING - The malt is milled into a coarse flour (grist), and added to hot water to activate the enzymes which will convert starches to fermentable sugars. Long starch chains are broken into glucose, maltose, and maltriose, which yeast is able to ferment. The extraction is done in a large kettle (usually made of stainless steel) called a mash tun. At first, the hot water activates the enzymes by providing an optimal temperature for activity in the grist. The enzymes act on the starch to convert it into sugar, and producing a sugary liquid called wort.

FERMENTATION - Yeast is added to the wort in a large vessel (often tens of thousands of litres) called a washback. The yeast feeds on the sugars and as a by-product produces both carbon dioxide and alcohol; this process is called fermentation and can take up to three days to complete. When complete, the liquid has an alcohol content of 5 to 7% by volume, and is now known as wash. Up until this point, the process has been quite similar to the production of beer.

DISTILLATION - The wash is then pumped into a copper pot still, known as the wash still, to be distilled. The wash is heated, boiling off the alcohol, which has a lower boiling point than water; the vapour is collected in a condenser which has been submerged in cool water. The lower temperatures cause the vapour to condense back into a liquid form. This spirit, known as low wine, has an alcohol content of about 20 to 40%. The low wines are then pumped into a second pot still, known as the spirit still, and distilled a second. The final spirit, called new make spirit, generally has an alcohol content of 60 to 70%. Much of the body, or mouth feel, of the final whisky is believed to come from the size and shape of the stills used in its production. When a still wears out and has to be replaced, or when a distillery decides to expand the number of stills it operates, precise measurements of the existing stills are taken to ensure the new stills are exact reproductions of the old.

MATURATION - The “new-make spirit”, or unaged whisky, is then placed in oak casks to mature. By law, all Scotch whisky must be aged for a minimum of three years in oak casks in Scotland, though many single malts are matured much longer. The whisky continues to develop and change as its time in the wood. Single Malt Scotch is too delicate to be aged in new oak casks, as new oak would overpower the whisky with tannin and vanillin, making it overly astringent. Thus used casks are needed.

BOTTLING - To be called a single malt Scotch, a bottle may only contain whisky distilled from malted barley produced at a single distillery. If the bottle is the product of single malt whiskies produced at more than one distillery, the whisky is called a vatted malt, or a blended malt. If the single malt is mixed with grain whisky, the result is a blended Scotch whisky. Single malts can be bottled by the distillery that produced them or by an Independent Bottler. The age statement on a bottle of single malt Scotch is the age of the youngest malt in the mix, as commonly the whiskies of several years are mixed together in a vat to create a more consistent house style. On occasion the product of a single cask of whisky is bottled and released as a “Single Cask.” While “cask-strength”, or undiluted, whisky (often having an alcohol content as high as 60%) has recently become popular, the vast majority of whisky is diluted to its “bottling strength” — between 40% and 46% ABV — and bottled for sale.

Flavor, aroma, and finish differ widely from one single malt to the next. Single Malt Scotch whiskies are categorized into the following whisky-producing regions.

(1) The highlands: The largest Scotch whisky producing region which embrace wide variations of whiskies

(2) The lowlands: defined as the area south of a line between Dundee and Greenock

(3) ISLAY: relatively small island 70 miles to the west of Glasgow and is inaccessible by road.

(4) The islands: sometimes placed together with the Highlands. In reality it includes all the islands other than Islay, notably Jura, the Orkney Isles, Mull and the Isle of Sky and the Isle of Arran.