The main grain used in the production of Scotch whisky is barley. In particular, single malt Scotch must be made from 100% malted barley, water, and yeast, then distilled in copper pot stills at one distillery.
Barley is malted by soaking it, allowing it to germinate, and drying it. This process develops enzymes that convert the grain’s starches into fermentable sugars. The dried malt is mashed with hot water, fermented into a beer-like liquid, and distilled before maturation in oak casks for at least three years.
A common mix-up is assuming every Scotch whisky uses only barley. Grain Scotch whisky may also contain wheat, corn, or other cereals, although malted barley is still required. Most Scotch sold worldwide is blended whisky, combining malt whisky with grain whisky.
The earliest known written reference to Scotch whisky dates to 1494, when malt was recorded in the Scottish Exchequer Rolls.