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Whiskey (Whisky)

an alcoholic beverage distilled from grain and malt

Whiskey is distinguished from other distilled alcoholic beverages by being aged in wood barrels a minimum of two years and by not being flavored by anything other than the grains used to produce it and the wood in which it is aged (by contrast, vodka is often bottled as soon as the distilling process is complete, and gin is flavored with berries). Although just about any cereal grain can be used to make whiskey, barley and corn are the most common, followed by rye and wheat; and, all whiskies must use at least some barley malt in order to start the fermentation process.

The origins of whiskey are not entirely clear, but legend says that St. Patrick introduced the distilling process to Ireland in the fifth century A.D. and that knowledge of the process then made its way to Scotland. The first written records of whiskey-making are found in Scotland and date to 1494.

How Whiskey Is Made

typical mash tunwhiskey stillsThe first step in making whiskey is to grind the grains into a meal, which is then mixed with water and cooked at a temperature of 212 F or more in order to create a mash. The mash is then transferred to a mash tun, where malted barley (barley that has been allowed to sprout) and water are added. The mixture is constantly stirred in order to help the malted barley convert the starches in the mash into sugars. This process takes several hours, after which a sugar-rich liquid called wort is drawn out; the left-over solids are usually made into cattle feed. Next, yeast is added to the wort and the mixture is allowed to ferment. Fermentation changes the sugar into alcohol. Some distillers use a new yeast culture for every batch of whiskey (known as the sweet mash process), while others use yeast cultures from a previous batch (the sour mash process). A liquid containing about 10% alcohol is produced after three or four days, and the liquid is distilled down until it reaches an alcohol content of at least 80%.

The major difference in making whiskey as opposed to most any other distilled spirit begins after the distillation process ends. Many spirits are bottled soon after distillation, but by international convention the distilled product must be aged for no fewer than three years before it can legally be called whiskey. During this time the liquid absorbs some of its final flavor from the barrel in which it is aged. In the United States whiskey must be aged in new barrels, but some distillers use barrels that are charred on the inside, which gives the final product a darker color and stronger taste than whiskey aged in uncharred barrels. Distilleries in Scotland often use barrels previously used to age American whiskey, and residual traces of that American whiskey add their own distinct flavors to the final product.

Once the aging process is finished the whiskey can be bottled, and it is at this time that the final differences in taste can be introduced by the various distilleries. Some brands of whiskey are bottled straight from the barrels in which they are aged, while others are bottled using different barrels from different batches in carefully calculated ratios. In addition, some brands have water added in order to lower the overall alcohol content (although it must still be at least 80% alcohol by volume).

Types of Whiskey

American Blended Whiskey must contain at least 20% straight whiskey, and some premium brands may blend as many as 75 different straight whiskies to produce one batch of final product.

Bourbon must, under U.S. law, be made from mash consisting of at least 51% corn, be distilled to 80% alcohol by volume or more, and be aged a minimum of two years in new, charred barrels. No blending of batches or use of additives other than water is allowed. Although it got its name from Bourbon County, Kentucky, bourbon can be produced in any state. And, while no international law exists giving the United States the exclusive right to produce bourbon, in order for it to be sold in the United States it must be made in the United States.

Canadian Whiskey can, by international convention, only be produced in Canada. Made primarily of corn or wheat supplemented with rye, barley, or barley malt, Canadian whiskey must be aged in used oak barrels for a minimum of three years. Most Candian whiskies are a blend of various batches covering a span of many years.

Irish Whiskey is usually a blend of pot-stilled malted and unmalted whiskey and column-stilled corn-based whiskey. The malt itself is always dried in a closed kiln, away from fire and smoke. It is aged in used bourbon or wine barrels for a minimum of three years. Although Ireland is the most predominant supplier of Irish whiskey, no international laws exist saying that it must only be produced in Ireland.

Rye must, under U.S. law, contain at least 51% rye mash, with the other 49% usually comprised of barley and wheat. It can be produced in any country, however, and some imported ryes may be made almost entirely from rye mash.

Scotch Whisky can only be made in Scotland. By Scottish law, Scotch can only be made from barley mash, no other grains may be introduced. What makes Scotch distinct from other whiskies is the malt drying process. Part of that process is done over a peat-fueled fire, which allows the smoke to come in direct contact with the malt, and that smokiness is transferred to the whisky during the fermentation process.

Tennessee Whiskey must be distilled from mash containing between 51 and 79% corn and can only be produced in Tennessee. Unlike other whiskies, Tennessee whiskey is filtered slowly through 10 feet of sugar-maple charcoal for up to two weeks before being transferred to barrels. Like bourbon, Tennessee whiskey is aged in new, charred oak barrels for a minimum of two years.

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The Robinson Library >> Technology >> Chemical Technology >> Fermentation and Distillation Industries

This page was last updated on February 25, 2017.