Bourbon 101 : GoToLouisville.com Official Travel Source

Bourbon is an American Whiskey produced primarily in Kentucky, where 95% of the world's bourbon is made (and 1/3 of that comes from Louisville). While bourbon does not have to be made in Kentucky, it must be made in the United States.

There are specific guidelines that distillers must follow in order to put the word bourbon on the label.

The Process - Most bourbon starts with sour mash. It is taken from a previous batch of mash (crushed grain going through the fermentation process), set out to sour overnight, and then added to a new batch. The process is much like that of starting sourdough bread.

The Recipe - Bourbon is distilled from a fermented mash of grain, yeast and water. The “mash bill” must have a minimum of 51% corn. For most bourbons, the average is about 70%. Other grains such as rye, malted barley and wheat are considered the “flavor” grains.

Length of Aging - In order to be considered straight bourbon, it must be aged for a minimum of two years. (If aged for less than four years, there must be an age statement on the bottle.) Many premium bourbons on the market are aged between 5 -12, with some as long as 27 years.

The Barrel - Bourbon must be aged in brand new, charred white oak casks (barrels). Brands determine the varying levels of char for their barrels from 1 to 4.

Flavor – By law nothing can be added at bottling except water. Nothing is added that might enhance flavor, add sweetness or alter the color.

Proof - Bourbon leaves the still at no higher than 80% alcohol by volume. It enters new charred white oak casks for aging at no higher than 62.5% abv. Bourbon is bottled at no less than 80 proof (40% abv). Only water may be used to lower the proof of the alcohol.

Location – Bourbon can be made anywhere in the US. Only whiskey produced in the State of Kentucky can be labeled Kentucky Straight Bourbon Whiskey.

Bourbon Glossary

Age: Often this is used as a measure of quality. It is not always dependable, however, because ingredients are a factor.

Aging: The process of letting whiskey mature in oak barrels picking up additional flavors of the wood. Once it is bottled no further aging takes place.

Angels' Share: A term common to whiskey and wine making. A certain amount of the spirit stored in a barrel evaporates through the wood. Roughly 2% of each barrel is lost this way, most of which is alcohol.

Backset: The alcohol-free liquid left at the bottom of the still after distillation is added to the mash tub and fermenter to ward off bacterial contamination.

Beer: Also known as wash. The alcoholic liquid that goes into the still.

Brewing: The process of mashing grain in hot water and fermenting the result with yeast to produce wash or beer.

Charring: The inside surfaces of new barrels are exposed to flames as part of the barrel-making process. This charring affects the flavor and color of the spirit aged in the barrel. New charred barrels are used only once in the production of bourbon. Other whiskies re-use their barrels or purchase used bourbon barrels.

Column Still: Invented in the 19th century to keep up with demand, this was the cheaper and faster alternative to the pot still.

Congeners: Chemical compounds produced during fermentation and maturation. Congeners are the natural flavor constituents in spirits. They are traces of oils, esters and acids carried through the distillation process and into the distillate. Spirits distilled at lower proofs have the highest congeneric content. High proof neutral spirits are practically free of congeners. Their presence in the final spirit must be carefully judged; too many would make it undrinkable.

Distillation: The process of separating the components in a liquid by heating it to the point of vaporization, then cooling so it condenses into a purified form.

Distiller's Beer: The fermented mash that is transferred from the fermenter to the beer still for the first distillation

Doubler: A large copper still which looks somewhat like a small water tank with an upturned funnel on top, used to distill high wines or new spirit from low wines.

Fermentation: The process by which microorganisms digest and convert carbohydrates to a liquid and a gas

Fermenter: The vessel in which the mash is distilled into alcoholic liquid, or wash.

Grain: The seeds of a cereal crop such as corn, rye, wheat, barley, etc.

Grain Neutral Spirits: Alcohol distilled from grain at 190 proof. Contains no noticeable aroma, flavor or character.

Mash: The liquid mass of fermenting grains from which spirits are distilled.

Mash bill: The recipe for the amounts and types of grains used in the mash.

Master Distiller: The person who determines the recipe for the distilled spirit and oversees its production.

New-Make Spirit: Spirit just off the still, before aging. Also called “white dog”.

Pot Still: Stills used for batch distillation. In pot still distillation the liquid is distilled usually twice, occasionally three times, first in a wash still and then in a spirit still.

Prohibition: National Prohibition in the U.S. ran from January, 1919 through December 5, 1933. During that period, beverage alcohol could not be legally produced, transported or sold. Limited exceptions were for medical purposes.

Proof: A statement of alcohol content. Proof is two times the percentage of alcohol by volume. For example, 100 proof equals 50% alcohol.

Rackhouse: The building in which whiskey is aged. Also referred to as the warehouse or rickhouse.

Ricks: The wooden structures on which barrels of whiskey rest during aging.

Sour Mash: Like sourdough bread that uses a “starter” from the previous day’s dough, this process provides uniformity in bourbon production. A portion of the previous day's mash is added to new mash to ensure consistent quality and character.

Still: The container in which the distiller's beer is purified by means of heating the liquid to at least 176 degrees Fahrenheit, but less than 212 degrees Fahrenheit. Because alcohol boils at a temperature lower than water, the alcohol can be evaporated, collected, and condensed.

White Dog: The colorless unaged distillate, just as it comes from the still and before it goes into the barrel for aging. Sometimes called "green whiskey" or "high wine” or “new-make”.