Nearly all the world’s whiskey is made in the US, Canada, Scotland, and Ireland. Bottles stand side-by-side on liquor store shelves in their various shades of amber, each with its own provenance, some with a list of awards it has won, many in fancy and ever more resplendent packaging depending on age and price. Each, from the humble $15 rotgut that says nothing more than “blended whiskey,” to the $250 bottle of 30-year-old, pedigreed Scotch, has its own distinct taste and is unlike the bottles standing next to it. There are two reasons for this difference.
THE GRAIN
Corn, rye, barley, wheat, and (rarely) oats are used in various combinations to produce whiskey.
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Bourbon, by law, is made exclusively in the US with at least 51% corn. Higher percentages of corn may be used (most often it’s 70-80%) with the remainder being rye and malted barley. Corn gives a light, sweet taste, barley is rich and mellow, and rye adds spice. Some bourbons, such as Maker’s Mark, use wheat instead of rye to produce a smoother flavor profile.
- Single-malt Scotch is made exclusively from malted barley. Barley dried in a kiln gives a rich, distinctive taste. Adding peat to the drying fire gives a smoky flavor, plus additional briny, medicinal overtones if the peat comes from a salt-water coastal area. Blended Scotch is a mix of any number of different single-malts plus grain whiskey made from corn or other grains.
- The distinctive taste of Irish whiskey comes from use of malted and unmalted barley. A few Irish whiskeys are smoky from peat-fire drying but most have the rich, mellow, pleasant barley flavor.
- Canadian whisky combines a predominant base whisky, usually made from corn, and a flavoring whisky often made from rye. There are no percentage requirements prescribed by Canadian law. Distillers strive for the light, consistent, appealing flavors their products have had for decades.
- US corn whiskey must be at least 80% corn, rye whiskey must be at least 51% rye, and wheat whiskey must be at least 51% wheat; other ingredients are determined by the distiller’s formula. Whiskey meeting none of these levels has unstated quantities of any number of grains and is simply called “blended.”
THE AGING
Bourbon is aged in new, charred, American oak barrels. Canada, Scotland, and Ireland have no requirements for use of new barrels and reuse them several times to age their products. After some Scotch and Irish whiskies have aged a certain length of time, they are transferred to imported bourbon, port, or Madeira barrels and aged longer to give the flavor added depth and character.
The longer a product remains in the barrel, the more it seeps into and out of wood cells and the deeper and more robust the flavor becomes. Thus older is usually better. Sampling 10-, 12-, 15-, and 18-year-old versions of Macallans Scotch, for example, reveals the slow development of its character from tasty and pleasant to rich and complex. Where a barrel ages is also a factor. Those on upper floors of a barrelhouse experience wider temperature variations. The product they contain sinks deeper into the barrel and takes on a different taste.
Small batch refers to blending a few to several dozen barrels to achieve and unique flavor. A Four Roses small batch bourbon sold today will likely taste somewhat different than the Four Roses small batch product sold in five years. Single barrel is just that: one barrel is selected for its superior taste and sold for a higher price, and then it’s gone. The next single barrel offering of the same label may taste similar or it may not. No one but the master distiller who created it will notice.
Thus but two simple variables, grain and aging, quickly generate myriad combinations to keep liquor store shelves stocked with hundreds of standards as well as new and ever-different products.