Whisk(e)y at the most basic level is distilled alcohol produced from fermenting a mash of grain — or corn in some cases. Making it initially shares a lot similarities with beer, minus the addition of hops. It starts by steeping a mixture of grains in hot water. That process triggers the release of the natural sugars which are then converted by yeast into alcohol. The resulting beer-like substance, called “wort” in whisk(e)y speak, is then distilled and put into wooden barrels to age. The type of grains used in the recipe, the distillation method and the barrels the spirit is stored in are what create the main differences between Scotch, bourbon, Irish, Canadian whisky and other types beyond their country of origin.
All Scotch whisky must be produced at a Scottish distillery from a recipe that includes water and malted barley, though other types of whole cereal grains can be used in addition. The resulting liquid must then be distilled at a strength of no less than 94.8% ABV (190 proof) and aged in Scotland in oak casks no larger than 185 gallons for a minimum of three years. After aging, the whisky must be bottled at a minimum of 40% ABV (80 proof). It’s not something the industry likes to talk about, but Scotch can have the caramel coloring agent E150A added to it for aesthetic purposes.
A variety of Scotch subtypes sit underneath this broad legal umbrella, some of which are more familiar to the average tippler than others.
Single Malt: A scotch produced exclusively in pot stills at one distillery from only malted barley and water is called a single malt. The single in this case refers to the distillery, not a grain type or barrel. While single malts are not blended with other whiskies made from various recipes, a bottle does contain a blend of the same Scotch recipe produced in different years and aged for various amount of time. This process is conducted by a master blender to insure a consistent flavor profile over years. The age statement on the bottle must reflect the youngest whisky used in the blend.
Speyside, Highlands, Lowlands, Islay and Campbeltown are the names of Scotland’s five main single malt producing regions. Usually the single malts from these regions share a common style or flavor profile, though it’s not set in stone. The Speyside region is by far the biggest producer and contains nearly half of all the whisky distilleries in Scotland.
Many associate a smoky flavor profile with Scotch, but it is not a requirement. The characteristic comes from peat — a mud-like substance which is burned by many Scotch distilleries to dry malted barley.
Single Grain: Like single malts, single grain Scotch whisky must be made and distilled at a single distillery. The difference is that other cereal grains can be used in the recipe along with malted barley.
Blended Scotch Whisky: This whisky is created by blending single malt Scotch whiskies with one or more single grain Scotch whiskies. Roughly 90% of Scotch whisky sold in the world is made in this way.
Blended Malt Scotch Whisky: Sometimes called a vatted malt or pure malt, this is a blend of one or more single malts made by more than one distillery.
Blended Grain Scotch Whisky: A blend of single grain Scotch whiskies made by more than one distillery.
The legal definition of Irish whiskey is relatively simple compared to Scotch or bourbon. It must be made and aged in Ireland. The resulting liquid must also be distilled from grains at a strength of no less than 94.8% ABV (189.6 proof) and aged in wooden barrels no larger than 185 gallons for a minimum of three years.
One of the primary differences between Irish whiskey and Scotch is the types of grains that are used in the recipe. Both malted and unmalted barley are common in Irish whiskey. Corn, wheat and rye can be added to recipes as well.
Many also associate Irish whiskey as being “smoother” than Scotch because it’s normally triple distilled (compared to the double distillation common with Scotch) and lacks the smoky influence of peat — but this is an over simplification. There are several examples of Irish whiskey that break these stereotypes.
Like Scotch, several Irish whiskey subtypes exist. They’re divided by distillation method (column still vs. pot still) and whether or not a bottle contains a blend of various recipes. Irish whiskey is enjoyed worldwide, but styles are limited compared to Scotch. That’s because Ireland has only a handful of operating distilleries compared to the roughly 125 in Scotland.
Blends: Irish whiskey made from a blend of various Irish whiskeys that include different grain mixtures.
Single Grain Whiskey: Irish whiskey made by a single distillery from a blend of corn, wheat, rye and barley in any combination. Most of it is produced using a continuous column still.
Single Malt: Irish whiskey made at a single distillery using a mash of only malted barley and distilled in a pot still.
Single Pot Still: Irish whiskey made by one distillery from a mixture of malted and unmalted barley that’s distilled exclusively in a pot still. This style is also known as “pure pot still”.
Canadian law states that whiskies produced in the country can be labeled Canadian Whisky, Canadian Rye or Rye Whisky. It can be made from any type of mashed grain and must be distilled and aged for at least three years in wooden barrels no larger than 185 gallons. The final product must be bottled at a minimum of 80 proof. Unlike most other standards, Canadian distillers can add caramel coloring and flavoring to their product to improve “marketability”.
While recipes differ from brand to brand, most contain a blend of lower-proof rye-based whisky with higher-proof whisky made from other grains, along with corn-based whisky for flavoring. Corn is often the primary ingredient of most bottles as a result, despite the frequent references to rye in the industry.
The ability to add sweetener and the heavy use of corn in this whisky’s production generally gives the category a “lighter” taste profile compared to other styles.
There are a variety of different types of whiskey being made in America, though bourbon and Tennessee whiskey are what most think of. Legally, federal regulations require a few basic stipulations are met. All American whiskey must be made from a mash of grain distilled at less than 80% ABV (160 proof), stored in new oak containers (except in the case of corn whiskey) and bottled a minimum of 40% ABV (80 proof). Other rules come into play with various subsets.
Rye, Wheat, Malt and Rye Malt Whiskey: These are American whiskeys where 51 percent of the mash bill recipe is composed of the namesake ingredient. No amount of aging time is required by law. Corn whiskey is subjected to the same rules, except that it does not have to be stored in wood. And if it is put in wood, it must be stored in un-charred or used oak barrels. These exceptions are designed to separate general corn whiskies from bourbon.
American Straight Whiskey: Straight whiskey adds a minimum aging requirement of two years to the same rules above. Whiskies made that follow this additional regulation can add “straight” on the label, i.e. straight rye whiskey.
Examples: Sam Houston Straight Whiskey
Bourbon: Bourbon must be made in the United States from a recipe with a minimum of 51 percent corn, making it technically a corn whiskey. However unlike generic corn whiskey, it must be stored in charred new oak barrels at no more than 62.5% ABV (125 proof). No amount of minimum aging is required by law. It also doesn’t have to be made in Kentucky.
Tennessee Whiskey: This offshoot of American whiskey isn’t defined federally in a strict legal sense like other American whiskey styles. It is, however, one of the biggest forces in the industry thanks to the global brand of Jack Daniel’s. Most Tennessee whiskey is made in exactly the same manner as bourbon except for a final step known as the Lincoln County Process. The method is named after the original county where Jack Daniel’s first distillery was located and involves pouring the distilled whiskey through a charcoal filter to remove impurities before barreling.
Further Reading & Expertise
Scotch Whisky Categorires from the Scotch Whisky Association.
Scotch Whisky Regulation Guidance 2009
United States, the Code of Federal Regulations Wiskey Definitions
Whisky 101 from Whisky Advocate.
Canadian Whisky from Wikipedia.
Irish Whiskey from Wikipedia.