Scotch whiskey is a traditional malt liquor that has been made in Scotland for centuries. The main ingredients in Scotch whiskey are barely and water. Yeast is used in the fermentation process and sometimes peat smoke is added for flavor. Though the ingredients are simple, the distillation process gives Scotch whiskey its signature flavor.
Scotch whiskey is made from malted barely. Whiskey brewers soak the barley grains or seeds in water for 2 to 3 days until they sprout. During the germination process, starch within the barley is turned to sugar. That sugar is later turned into alcohol. Once the barely begins to sprout, the grains are removed from the water and dried. The sprouted barely is then moved to a kiln to stop the process of germination.
The barley is placed in an oven or kiln to end the malting process. In traditional Scotch whiskey production, the kiln was peat fired. This gave the whiskey a "peaty" flavor unique to Scotland. Today, most ovens are powered by conventional means. However, some distilleries blow peat smoke over the barley to give their whiskey a traditional flavor.
Once the barley grains are dried, they are ground in a mill. The ground barley, called grist, has a consistency much like flour. The grist is mixed with hot water in a mash turn, which stirs the concoction regularly. At this stage the barley is called mash. Grinding the mash works to release the barely starch and convert it into fermentable sugar. The resulting liquid, known as wort, is separated from the mash. The remaining solids, now called draff, is often recycled as cattle feed.
The wort is put into washbacks, which are wooden pails often made from Oregon pine or Cypress and are resistant to fungi. Yeast is added to the wort to begin the fermentation process. Fermentation takes between 2 to 4 days. At the end of this process, the liquid, now called wash, will taste very similar to beer and will have an alcohol content of less than 10 percent.
Natural fermentation will not usually yield a beverage with an alcohol content over 15 percent. As a result, liquors are distilled to achieve higher levels of alcohol content. No new ingredients are added at this stage. The wash is placed in a copper wash still and then heated. Since alcohol has a lower boiling point than water, the alcohol separates from the water and collects in the still's swan-shaped neck. The liquid collected in the neck has an alcohol content between 10 to 20 percent. The collected alcohol is further heated and distilled in a smaller spirit still. The resulting liquid collected in the spirit still's neck is more concentrated and has a higher alcohol content. Distillation may be repeated many times in the spirit still to achieve the desired alcohol level and taste.