Some key types listed in the U.S. Code of Federal Regulations are:
- Rye whiskey, made from mash that consists of at least 51% rye
- Rye malt whiskey, made from mash that consists of at least 51% malted rye
- Malt whiskey, made from mash that consists of at least 51% malted barley
- Wheat whiskey, made from mash that consists of at least 51% wheat
- Bourbon whiskey, made from mash that consists of at least 51% corn (maize)
- Corn whiskey, made from mash that consists of at least 80% corn
Unless the whiskey is labelled as blended, to be labelled as one of the types listed above, the whiskey must be distilled to not more than 80% alcohol by volume (160 U.S. proof) to ensure that the flavour of the original mash is adequately retained, and the addition of colouring, caramel and flavouring additives is prohibited. All of these except corn whiskey must be aged (at least briefly, although no minimum aging period is specified) in charred new oak containers. These restrictions do not exist for some similarly named products in some other countries, such as Canada. American corn whiskey does not have to be aged at all – but, if it is aged, it must be aged in used or uncharred oak barrels,”at not more than 62.5% alcohol by volume (125 proof)”. In practice, if corn whiskey is aged it usually is aged in used bourbon barrels.
Straight whiskey is whiskey that was distilled to not more than 80 percent alcohol by volume (160 proof) that has been aged for at least two years at a starting alcohol concentration of not more than 62.5% and has not been blended with any other spirits, colourings, or additives. A straight whiskey that also meets one of the other above definitions is referred to by combining the term “straight” with the term for the type of whiskey. For example, a rye whiskey that meets this definition is called a “straight rye whiskey”.
Unqualified “whiskey” without a grain type identification such as “bourbon”, “rye” or “corn” must be distilled at less than 85 percent alcohol by volume (190 proof) from a fermented mash of grain in such a manner that the distillate possesses the taste, aroma, and characteristics generally attributed to whiskey, and must be stored in oak containers (charred new oak is not required), and bottled at not less than 40 percent alcohol by volume (80 proof). To carry the designation “straight whiskey” without a grain type identification, the fermented mash must be less than 51 percent of any one type of grain and must be stored for a period of at least 2 years in charred new oak containers.
A straight whiskey that has been aged less than four years is required to be labelled with an age statement describing the actual minimum age of the product, whereas if straight whiskey is stored as prescribed for four years or more, a statement of age is optional.
Furthermore, a straight whiskey (or other spirit produced from a single class of materials) may be labelled as bottled in bond if it has been aged for at least four years in a federally bonded warehouse, is bottled at 40 percent alcohol by volume (100 proof), and is the product of one distilling season.
Other types of American whiskey that are defined by federal regulations include the following:
- Blended whiskey is a mixture which contains straight whiskey or a blend of straight whiskeys containing not less than 20 percent straight whiskey (on a proof gallon basis), and, separately or in combination, other whiskey or neutral spirits. For the blended whiskey to be labelled with a particular grain type (i.e., to be labelled as blended rye, malt, wheat, or bourbon whiskey), at least 51% of the blend must be straight whiskey of that grain type. The part of the content that is not straight whiskey may include un-aged grain distillates, grain neutral spirits, flavourings, and colourings.
- Blend of straight whiskeys is a mixture of one or more straight whiskeys that either includes straight whiskeys produced in different U.S. states or colouring and flavouring additives (and possibly other approved “blending materials”), or both, but does not contain grain neutral spirits.
- Light whiskey, which is produced in the United States at more than 80% alcohol by volume and stored in used or uncharred new oak containers.
- Spirit whiskey, which is a mixture of neutral spirits and at least 5% of certain stricter categories of whiskey.
However, it is important to note that these various labelling requirements and “standards of identity” do not apply to products for export from the U.S. (under C.F.R. Title 27, § 5.1). Thus, exported American whiskey may not meet the same labelling standards when sold in some markets.
Another important American whiskey labelling is Tennessee whiskey. There are only four brands of Tennessee whiskey that are currently bottled – Jack Daniel’s, George Dickel, Benjamin Prichard’s, and Collier and McKeel. Three of the four brands of currently produced Tennessee whiskey use a production process that involves a filtering stage called the Lincoln County Process, in which the whiskey is filtered through a thick layer of maple charcoal before it is put into casks for aging. Tennessee whiskey is a recognized name defined under the North American Free Trade Agreement (NAFTA), at least one other international trade agreement, and the law of Canada as a straight bourbon whiskey lawfully produced in the state of Tennessee. In 2013, Tennessee House Bill 1084 was passed, requiring the Lincoln County process to be used for products produced in the state labelling themselves as “Tennessee Whiskey” with a particular exception tailored to exempt Prichard’s, and included the existing requirements for bourbon.