Single malt whisky

Single malt whisky is malt whisky from a single distillery.

Single malts are typically associated with single malt Scotch, though they are also produced in various other countries.

Under the United Kingdom's Scotch Whisky Regulations, a "Single Malt Scotch Whisky" must be made exclusively from malted barley (although the addition of E150A caramel colouring is allowed), must be distilled using pot stills at a single distillery, and must be aged for at least three years in oak casks of a capacity not exceeding 700 litres (150 imperial gallons; 180 US gallons).

Regulations in other countries largely follow the Scotch model, though permitted practices vary. For example, United States regulations state "[t]he adopted criteria for American single malt whisky specify that the product be a type of whisky that is mashed, distilled, and aged in the United States; is distilled entirely at one U.S. distillery; is distilled to a proof of 160 or less; is distilled from a fermented mash of 100 percent malted barley; is stored in oak barrels (used, uncharred new, or charred new) with a maximum capacity of 700 liters; and is bottled at not less than 80° proof. In addition, the criteria allow for the use of caramel coloring as long as its use is disclosed on the product label. The regulation will also allow the use of the term “Straight” for an American single malt whisky that is aged for at least two years."

Barley, yeast, and water are the only ingredients required in the production of (barley-based) single malt whisky. All single malt goes through a similar batch production process.

There are several types of single malts available from distilleries including single barrel single malts which are the product of a single batch that was stored for three or more years in a single oak barrel. These single-barrel variants afford the opportunity for the consumer to see the influence of different types of storage on the same whisky (e.g., first-use bourbon whiskey barrels, port pipes, etc.). The more common form of single malt is a marrying at the bottling time of various batches that are mixed or vatted to achieve consistent flavours from one bottling run to the next.

Barley is "malted" by soaking the grain in water for two to three days and allowing it to germinate. This process releases enzymes, which convert unfermentable starch (which is insoluble in water and not available for fermentation by yeast) to fermentable sugars. Traditionally in Scotland, germinating seeds were laid on a malting floor and regularly turned. After three to five days, when the optimum amount of starch has been converted to fermentable sugars, germination is halted by heating the seeds with hot air.

Many distilleries once used a kiln to heat the germinated barley. The "pagoda roof" (many now false) that ventilated the malt kiln can still be seen at many distilleries both in Scotland and in other countries. However, most of the distilleries now use commercial "maltsters" to prepare their malt.