Whiskey is an alcoholic product that has been made of cereal grain, distilled, and then aged in barrels. This is the most basic definition.Whiskey is a diverse and global spirits category, so the specific cereals used and the techniques of spirit creation do depend on where in the world its produced, their legal constraints, and distilling traditions. For this article I shall be focusing on Great Britain and the Republic of Ireland.
On the British Isles, whisky has to be distilled from cereal whole-grains with a malted component. In England, Wales and Scotland this has to be malted barley.
Ireland, having more freedom for creativity in their technical file can use any malted grain, so we are seeing the emergence (or resurgence) of malted rye and oats in mash bills.
A cereal is a grass that has been cultivated into and for its edible grain.
The grains of a cereal are its seeds. These seeds store energy as starch, in the same way that humans store energy as fat. This gives plants the energy to grow new plants. Yeasts, which are the microbes that make alcohol, cannot process starch so it is important to convert starches into usable sugars.
Using cereals as a raw material means that processing is required to break down the starches into usable sugars. These processes will be covered in a future post.
The recipe of the different cereals used in the making of whiskey is called the mash bill. If the mash bill contains 100% malted barley, that whiskey is a single malt. If there are other grains on the mash bill, that is usually classified as a grain whiskey, with a specific exception in Irish whiskey called single pot still.
Barley is the key cereal for making whiskey in the British Isles. Barley is a hardy cereal, growing well in cool temperate climates. Barley has a relatively low starch content(≈65%) when compared to maize or wheat, but its natural enzymes are incredibly efficient at converting starches into simple sugars, so can be used in mixed mashbills for the purpose of saccharification. Distillers only use certain varieties of barley, which have been purpose bred to improve yield and survivability. The biggest reason barley is used in distilling is that barley malt has a delicious aroma and flavour.
Wheat is hardy and plentiful, being grown all around the world, and has a high starch content(≈69%). This makes it an inexpensive and efficient distilling material. Wheat however isn’t a particularly flavourful grain so is usually used in bulk alcohols, or to soften mashbills.
Maize(corn) is not native to the British isles, and is predominantly grown in and sold from the United States of America. It is a key component of bourbon, and has a very high starch content(≈72%). It’s use in British grain whiskey has diminished somewhat with an increase in prices, but can still be found in the mashbill of a few distilleries.
Rye is becoming a more popular distilling grain, especially in Ireland. It is notoriously difficult to work with due to the presence of beta glucans that can create a sticky mash. It has a unique aromatic quality as well as a bread crust and spicy flavour that makes the effort well worth the reward.
