Whiskey is made from water, yeast, and grain. The water used is often considered the most important factor in making good whiskey. It should be clean, clear, and free from bad-tasting impurities such as iron. Water that contains carbonates, found in areas that are rich in limestone, is often used in the United States, particularly in Maryland, Pennsylvania, Indiana, and Kentucky. Scottish water is famous for being suited to making fine whiskey, for reasons that are still somewhat mysterious.
No one knows where or when the first grain spirits were produced, but they certainly existed in Europe no later than 500 years ago. Some claim that whiskey was invented in Ireland as long as 1,000 years ago and carried to Scotland by monks. In any case, the first written records of Scottish whiskey-making date as far back as 1494. (The word whiskey comes from the Irish Gaelic uisge beatha or the Scottish Gaelic uisge baugh, both meaning "water of life.")
Preparing the grain
Truckloads of grain are shipped directly from farms to the whiskey manufacturer to be stored in silos until needed. The grain is inspected and cleaned to remove all dust and other foreign particles. All grains except barley are first ground into meal in a gristmill. The meal is then mixed with water and cooked to break down the cellulose walls that contain starch granules. This can be done in a closed pressure cooker at temperatures of up to 311°F (155°C) or more slowly in an open cooker at 212°F (100°C). Instead of being cooked, barley is malted. The first step in malting barley consists of soaking it in water until it is thoroughly saturated. It is then spread out and sprinkled with water for about three weeks, at which time it begins to sprout. *During this germination the enzyme amylase is produced, which converts the starch in the barley into sugars. The sprouting is halted by drying the barley and heating it with hot air from a kiln. For Scotch whiskey, the fuel used in the kiln includes peat, a soft, carbon-rich substance formed when plant matter decomposes in water. The peat gives Scotch whiskey a characteristic smoky taste. The malted barley is then ground like other grains.
Mashing consists of mixing cooked grain with malted barley and warm water. The amylase in the malted barley converts the starch in the other grains into sugars. After several hours the mixture is converted into a turbid, sugar-rich liquid known as mash. (In making Scotch malt whiskey the mixture consists only of malted barley and water. After mashing the mixture is filtered to produce a sugar-rich liquid known as wort.)
The mash or wort is transferred to a fermentation vessel, usually closed in Scotland and open in the United States. These vessels may be made of wood or stainless steel. Yeast is added to begin fermentation, in which the single-celled yeast organisms convert the sugars in the mash or wort to alcohol. The yeast may be added in the form of new, never-used yeast cells (the sweet mash process) or in the form of a portion of a previous batch of fermentation (the sour mash process.) The sour mash method is more often used because it is effective at room temperature and its low pH (high acidity) promotes yeast growth and...