How Whiskey is Made
Whiskey production varies depending on the style being made, the country where it originates, and other factors, but the general process remains the same in most cases. The process involves choosing a grain, fermenting it, distilling the liquid, then aging the liquid.
Grain Selection and the Mixture (The Mash Bill)
Each distillery has its own recipe for the grain mixture, that recipe is called the “Mash Bill.” The primary grains in the mash bill are either Barley, Rye, Corn, Wheat, or a mixture of those elements.
Barley
Barley is a cereal grain that was originally native to Asia. Barley was very important in ancient times and was one of the first grains to be widely cultivated. However, when leavened bread became popular, consumption of barley was replaced by wheat and rye. Having a lower gluten content (which provides the framework for dough to rise), the application of barley in the production of bread is limited. As such, fewer people today in developed countries eat barley. Although, the discovery that barley is high in beta-glucan has given rise to its use in health-promoting food products, especially foods tailored to cardiovascular health. Barley grows in either “6 row” or “2 row” varieties, and whiskey distillers will choose which variety they use based on the characteristics of the whiskey the produce.
A large proportion of the world’s barley supply is used make beer. Barley does however remain a staple food for many people in less developed countries such as those in North Africa and in areas where wheat is difficult to grow, such as Tibet.
The term “Green Barley” simply means “Unmalted barley,” and refers to barley that is taken straight off the plant and used, instead of being malted. The Redbreast brand is a whiskey that uses unmalted barley in its mash bill
Rye
Rye came into cultivation later than wheat, barley, and oats and was not known to the ancient Egyptians and Greeks. It was the main grain used for bread-making in Northern Europe and Russia for many centuries. This is partly because it grows well in colder, harsher climates and partly because it was preferred by some people.
Scandinavian countries such as Denmark, Norway and Sweden eat a variety of bread and crispbreads made from rye flour, although wheat products are becoming more popular.
Rye contains less gluten than wheat flour, and this makes rye bread significantly denser. Traditional rye breads are made with a sourdough method so have a slightly sour taste when compared to wheat bread. Dark rye flour bread is all whole grain flour. Light rye grain bread is a mixture of whole grain rye flour and refined rye flour. Bread made wholly from rye flour is made in Germany and called pumpernickel
Corn
Corn (also known as maize), is one of the sweetest tasting grains. In its immature form it is the familiar yellow corn on the cob. When it matures and dries out it is used like other grains to make grain foods like breakfast cereal and tortillas. It is one of the world’s most important crops because it is used widely in food manufacture.
Corn is unique in that it cannot reproduce itself without the aid of humans – its seeds cannot be released because they are tightly wrapped around the ear. Wild corn has never been found and domesticated corn was probably developed through hybridization.
Wheat
Few distilleries add wheat to their mash bill (e.g. Bernheim or Maker's Mark). Wheat makes a whiskey milder and smoother on the tongue. If wheat is added, it makes up about 10% of the mash bill.
Malting
All whisky starts as raw grain—in the case of malt whisky, barley, which has to be specially treated to access its sugars. The barley is moistened and allowed to partially sprout, or germinate, a process called malting which secretes an enzyme that converts the barley’s starches to sugars. Germination is cut off when the barley is dried by heating.
Mashing
The sugars contained in the grain must be extracted before fermentation, and this is done through mashing. The grains that are being used—like corn, wheat, or rye—are ground up, put in a large tank (called a mash tun or tub) with hot water, and agitated. Even if the distiller isn’t making malt whisky, some ground malted barley is typically added to help catalyze the conversion of starches to sugars. The resulting mixture resembles porridge. Once as much sugar as possible has been extracted, the mixture—now known as mash or wort (if strained of solids)—moves on to the fermentation stage.
Fermentation
Fermentation occurs when the mash/wort meets yeast, which gobbles up all the sugars in the liquid and converts them to alcohol. This takes place in giant vats, often called washbacks. The process can take anywhere from 48 to 96 hours, with different fermentation times and yeast strains resulting in a spectrum of diverse flavors. The resulting beer-like liquid—called distiller’s beer or wash—clocks in at around 7%-10% ABV before it goes into the still.
Distillation
The process of distilling increases the alcohol content of the liquid and brings out volatile components, both good and bad. Stills are usually made of copper, which helps strip spirits of unwanted flavor and aroma compounds. The two most common types of stills—pot stills and column stills—function differently. Both are outlined below.