Single malt whisky Single malt whisky Single malt whisky is malt whisky from a single distillery, that is, whisky distilled from a fermented mash made with malted barley, as distinguished from unmalted grain. Single malts are typically associated with single malt Scotch, though they are also produced in various other countries. Under 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
Whisky in wood for a similar time. After a decade or two, additional aging in a barrel does not necessarily improve a whisky. While aging in wooden casks, especially American oak and French oak casks, whisky undergoes six processes that contribute to its final flavor: extraction, evaporation, oxidation, concentration, filtration, and colouration. Extraction in particular results in whisky acquiring a number of compounds, including aldehydes and acids such as vanillin, vanillic acid, and syringaldehyde. Distillers will sometimes age their whiskey in barrels previously used to age other spirits, such as rum or sherry, to impart particular flavours. Most whiskies are sold