About Bourbon

Bourbon is the only uniquely American spirit. It can only be made in the United States. About 95% of bourbon is made in Kentucky, but it can be made in any state.

Bourbon's mash bill must contain at least 51% corn. Any variety of corn can be used, but yellow dent corn is most often used. Some distilleries use heirloom varieties of corn. Bourbon can be 100% corn, but that is atypical. Usually, other grains are added for flavor or to convert the starches to sugars. Rye and wheat are the two most commonly used flavoring grains. Malted barley is most often used for its enzymatic properties, to break down the complex starches into simple sugars, which can be used for fermentation. Some distilleries have experimented with other flavoring grains, such as oats, rice, sorghum, millet and amaranth, among others. Some distilleries have used malted rye for its enzymatic properties. As long as the mash bill contains at least 51% corn, any combination of grains may be used.

Bourbons may contain a variety of yeast strains, most of which are proprietary to the distillery. The yeast is what ferments the sugars into alcohol. The product, or distiller's beer, is run through the still, which increases the alcohol content. A continuously operating column still may be used, particularly by large distilleries, or a smaller pot still may be used, particularly by craft distilleries, who want to achieve a more controlled flavor profile. The number of distillation runs may vary. Sour mash means a portion of the last distillation run is placed back into the new batch for fermentation. The yeast is gone, but the old mash adds consistency to the new mash. Sweet mash means everything in the new batch is new.

Bourbon may not come off the still at any higher than 160 proof. It may not be put into the container, generally a barrel, at any higher than 125 proof.

Bourbon must be aged in a new, charred oak container. Notice that it does not have to be a barrel, though I know of no commercially prepared bourbons that do not age in a barrel. The level of char usually varies from a level 1 at 15 seconds to a level 4 at 55 seconds. Some distilleries use an even higher level of char. American oak is most commonly used, but the oak can be sourced from any country. A bourbon barrel can never be used to make bourbon again, though it can be used for finishing other alcoholic beverages, including bourbon itself. There is no minimum age requirement for bourbon. As long as the liquid hits a new, charred oak container, it can be called a bourbon. However, it would not be fit to drink. A straight bourbon must be aged for at least 2 years. If a bourbon is aged for less than 4 years, it must contain an age statement on the label. Bourbons with no age statement guarantee that the youngest liquid in the bottle is aged for at least 4 years.

Nothing can be added to bourbon before bottling, except water. This is done to cut the bourbon down to bottling proof. A bourbon cannot be bottled at less than 80 proof. Many bourbons are bottled at barrel proof, or cask strength. This means no water is added at bottling. No artificial flavors or colors can be added to bourbon before bottling. All the flavors in bourbon come from the mash bill, the yeast strain, the charred oak of the barrel and the water. Chill filtration means the bourbon is filtered at a cooler temperature before bottling. This removes many of the oils, which allows the bourbon to remain clear when served on ice, but it also removes some of the flavor and the mouthfeel of the bourbon. Non-chill filtration means this step is omitted. The reason most bourbon is made in Kentucky is because of the water. It is filtered through limestone aquifers, which removes bad tasting iron and adds good tasting calcium and magnesium. The other reason is historical. Corn was the main crop of Kentucky, when it was the frontier of Virginia. All the colors of bourbon come from the barrel. The higher the char level and the longer the aging process, the deeper the color will be.

Straight bourbons can only come from a single state. A blend of straight bourbons from the same state can still be called a straight bourbon. A blend of bourbons from different states must be labeled as a blend of straight bourbons.

Bourbons can be finished in different barrels before bottling, but they must be labeled as such. They must meet all the requirements for bourbon before they are finished. Finished bourbons are aged for a shorter amount of time in different types of barrels, typically those used to age other types of liquor or wine. Some bourbons are finished in barrels that are toasted not charred, or in previously used bourbon barrels. Some bourbons are double barreled or double oaked. These are finished in a second new, charred oak barrel.

Bottled-in-bond means the bourbon must come from a single distillery in a single distilling season. It must be aged for at least 4 years, and it must be bottled at 100 proof. The barrels must be stored in a federally bonded warehouse.

Single barrel means the bourbon is bottled from a single barrel. It is not blended with other barrels. Therefore, single barrel bourbons of the same brand may vary significantly in proof and flavor from one another.

Small batch means a small number of barrels are blended together to achieve a certain flavor profile. The number of barrels varies between distilleries, but the number is usually under 50. This is distinct from large batches, which may contain hundreds of barrels, and are designed to achieve a consistent flavor profile.