Part of the grass family, barley is a cereal grain grown around the world. The grain was one of the first cultivated. It is also a key ingredient in beer and other distilled beverages, including whisky. Whisky in Scotland and Ireland are made primarily from barley, while other grains like corn, rye and wheat are used in whiskies produced in Canada and the United States.
Grain whisky refers to whisky made from grains, including barley. Other common grains used are corn, rye and wheat. Some grain whiskies may contain a mix of grains, including malted barley. There could be two or three different grains used to produce some whiskies. Using malted barley provides enzymes necessary for mashing, the process of combining grains with water and heat to break down the starch in the grains into sugars.
Compared with malt whisky, grain whisky has a milder or light flavour and aroma. There are generally hints of vanilla, citrus, honey and oak. The flavour and aroma will depend on which mix of grains are used to produce the whisky.
Types of Barley
Just like there are hundreds of varieties of grapes used to produce wine, there are many varieties of barley. There are about 5,500 strains of barley, although only a small fraction is used to make whisky. Only ten are approved by the Institute of Brewing and Distilling in Scotland for Scotch whisky production. These ten strains are all developed from the same strain, Hordeum distichon. They also have a limited effect on a whisky’s flavour. Most Scotches are made from barley produced on the eastern coasts of Scotland and England, where lower rainfall and sandy soils are ideal for growing. Canada, Australia and other parts of Europe are also main suppliers of barley used for whisky production.
For the most part, single malt Scotch is produced using two-row spring barley. Popular strains include Belgravia, Concerto, Optic, Propino, Quench and Shuffle. Chronicle, Moonshine, Odyssey and Overture are also used, although only more recently. New barley varieties are often tested with the hopes of higher yields. This has led to several varieties of barley no longer being used for whisky production, including Chariot, Golden Promise, Oxbridge, Prisma and Triumph.
For Malt whisky producers, two- and six-row barley strains with a low nitrogen content and consistently large grain size are preferred. Nitrogen content of between 1.2 to 1.65% by weight is usually used, although 1.5% is ideal. With more protein, a higher nitrogen content is usually used for producing grain whiskies as well as for animal feed. These grains are also high in starch, usually between 60 and 65%. These starches are essential since they are converted into larger amounts of sugar for fermentation. These grains are also easier to germinate, making them easier to malt. There is also good enzyme potential, which is also essential for converting starch into sugars during mashing. Certain enzymes are also needed for alcohol production.
Malted barley, or malt, is barley that has been allowed to germinate (or sprout) by being soaked in water. By doing this to the grain, the starches are converted into fermentable sugars. The process ensures that starch in the grain can be made into alcohol. This process is known as malting, an important step in the process of producing whisky as well as beer.
Malt whisky refers to whisky made from malted barley, differentiating them from grain whisky. Malt whisky is generally produced from mashing only malted barley whereas grain whisky can include a combination of malted and non-malted grains. Regulations in Ireland and Scotland specify that malt whisky must be produced by 100% malted barley. The flavour and aroma of malt whisky is typically strong and bold. It usually has hints of smoke, vanilla, fruit, wood and yeast as well as malt.
Single Malt Whisky
Single malt whisky is also made with only malted of one type of grain. In Scotland, the term is used to identify whisky made from only malted barley. The whisky must also be produced in one distillery and matured for at least three years in casks made from oak. Some producers in the United States and Canada use this term to refer to malt whisky made from only malted rye rather than barley.
The Malting Process
Malting first involves soaking or steeping barley. The grain is dormant, which ensures it does not start growing until the new growing season. Malting tricks the grain to start sprouting by making it think it is spring.
Grains are set in steeping tanks and soaked for a couple of days. The warm water is set at about 16 C or 60 F. By raising the grain’s moisture content, growth starts. The process starts with immersing the grain in water for a short period and then draining the water. Resting the grain outside of water, also known as wet stands, allows oxygen to enter the grain and activate the grain’s embryo. It also makes the grain ready to soak in more water when it is placed back in the water again. This process is usually repeated three times and the amount of time spent in and out of water is dependant on the grain.
After steeping, the barley is spread evenly across a concrete malting floor in a large room, also with a temperature of about 16 C or 60 F. The grains are turned regularly to avoid excess heat building up due to the germination process, usually at least twice a day. The humidity, temperature and airflow in the room are closely monitored. Any change could affect the malt’s properties. The drying process encourages the grain to germinate. The starch within the grains start to convert into sugars as the barley sprouts, making it easier to create alcohol when yeast is added during the fermentation process. Enzymes activated during this time are important for mashing. Germination takes places during a period of four or five days.
There is a balancing act when malting barley. You want to avoid allowing the grain to open or sprout too much. Typically, the malt is dried for about a week before it is put into a kiln. Producers stop germination with heat by using a maltsters kiln in a process known as kilning. The temperature of the kiln is slowly increased to around 49 C or 120 F over a period of 24 to 48 hours. This is high enough to stop germination but not enough to destroy the enzymes in the grain. The result is a dried grain with sugar and starch as well as diastase, one of the key enzymes for the next steps in producing whisky.
Since this process is labour intensive and takes up to seven days, many distilleries outsource malting to third-party maltsters. Malsters generally operate their own facilities and use mechanised methods for soaking and drying grains before they are shipped to distillers.
Malting’s Effect on Whisky Flavours
Malting does more than just make it easier to ferment grains into alcohol. The process also impacts the look and taste of the whisky as well as beers that are created from malted barley. The temperature used to dry grains will affect the colour of the beer or whisky. For a pale colour, for example, low temperatures are used. Increasing the temperature results in amber and darker colours. The process of drying the grains will also ultimately affect the whisky’s flavour. For example, a smoky flavour is achieved when peat is added when barley is dried in the kiln.
How Malted Barley is Used
Malted barley is used to create grain and malt whiskies. While producing each type of whisky involves similar steps, the initial process differs slightly. Once the grains are dried, the malt is ground into a coarse flour known as grist. The ground malt is then mixed with water in a large vessel or mash tun. The liquid is heated close to boiling. For grain whisky, un-malted grains are added after water is mixed with the malted barley. The sugars in the grains dissolve during the mashing process, resulting in a sweet liquid known as wort. This liquid is then passed in a large container or washback. Any spent grains are removed before the fermentation process, which involves adding yeast and allowing the sugars to convert into alcohol over a couple of days.