How is Scotch whisky made?
While each distillery in Scotland will have their own nuances regarding production, malt Scotch whisky is made through a meticulous process that typically involves six key steps.
1. Malting
Barley grains are soaked in water to allow them to germinate. Once germination begins, the barley is dried using hot air in a kiln, halting the germination process. This step converts the starches in barley into fermentable sugars.
2. Mashing
The dried malted barley, now called malt, is ground into a coarse flour called grist. The grist is then mixed with hot water in a large vessel called a mashtun, where the enzymes from the malt convert the starches into sugars, creating a sugary liquid called wort.
3. Fermentation
The wort is transferred to a washback which is a fermentation vessel (typically made of wood or stainless steel) where yeast is added. Yeast consumes the sugars in the wort, producing alcohol and carbon dioxide. This process typically takes around two to four days and results in a liquid called wash, with an alcohol content of around 7-10%.
4. Distillation
The wash is then distilled in copper pot stills, usually twice, sometimes three times. During distillation, the alcohol vapours rise through the still and are condensed back into liquid form. The result of the first distillation is known as "low wines," which undergo a second distillation to further purify and concentrate the alcohol.
5. Maturation
The distilled spirit, known as "new make spirit" or "distillate," is placed in oak barrels for maturation. These barrels are often previously used bourbon, sherry, or wine casks. The whisky matures over several years, during which it gains its characteristic flavours and colours from the wood.
6. Bottling
After maturation, the whisky is typically diluted with water to achieve the desired Alcohol By Volume (ABV) and filtered to remove any remaining impurities. It is then bottled and labeled for sale.
Malt whisky uses only three ingredients (water, barley and yeast). Grain whisky is produced slightly differently as it uses both malted and unmalted barley, cereals (maize, wheat), water and yeast as its raw materials. Grain whisky is also typically produced in a Coffey or continuous still whereas malt whisky must be produced in a pot still. See this blog post on the different categories of Scotch whisky.
Grain Scotch Whisky
Grain Scotch whisky is made using a different process compared to malt whisky. While malt whisky is made solely from malted barley, grain whisky is made using a mixture of malted barley and other grains, typically maize (corn) and wheat. Here's an overview of how grain Scotch whisky is produced:
Mashing
Just like malt whisky production, the grains are milled into a coarse flour called grist. The grist is mixed with hot water in a mashtun to extract sugars. The resulting liquid, called wort, contains a mixture of sugars from both malted barley and other grains.
Fermentation
The wort is then fermented using yeast, converting the sugars into alcohol. The fermentation process typically takes place in large vessels, similar to those used in malt whisky production.
Distillation
Unlike malt whisky, which is typically distilled in pot stills, grain whisky is often distilled in continuous column stills. These stills allow for continuous distillation, resulting in a lighter and smoother spirit. The distillation process is usually carried out multiple times to achieve the desired purity and alcohol content.
Maturation
After distillation, the new make spirit is aged in oak barrels, similar to malt whisky. The maturation process allows the whisky to develop its flavors and character over time. Grain whisky is often aged for shorter periods compared to malt whisky, although there are exceptions.
Blending
Grain whisky is used as a component in blended Scotch whisky, where it is combined with malt whisky to create a balanced and consistent product. Blending allows distillers to achieve a wide range of flavour profiles and styles. Overall, while the basic principles of whisky production remain the same for both malt and grain whisky, the use of different grains and distillation methods results in distinct characteristics and flavour profiles for each category.
