Bourbon

Bourbon is a type of American whiskey that uses corn as its primary distilling ingredient and is aged in charred oak barrels. The high percentage of corn in the mash and the char on the barrels help give bourbon its well-known sweet flavor. Bourbon producers must follow a particular set of rules to ensure their products meet the legal definition of bourbon. Bourbon gets its name from Bourbon County, Kentucky, where many types of bourbon are produced. Bourbons that are made and aged in Kentucky are called “Kentucky bourbon,” and this designation can make the product more desirable. Yet, a drink can be called bourbon even if it is not produced and aged in Kentucky.

Background

Distillation is a process that separates and purifies liquids. One of the most common modern applications of distillation is to create a concentrated alcohol, but other types of distillation—such as coal tar refining—are also important. The distillation process uses evaporation and condensation to separate components of liquid mixtures or to separate liquids from solids. Many historians believe that distillation first occurred thousands of years ago in the Middle East or Asia. The earliest practitioners of the process most likely used it to purify perfumes, cosmetics, or other materials. The distillation of alcohol is believed to be an accidental development, stumbled upon when the ancients were searching for an elixir of life. The Chinese may have been distilling alcohol from rice by about 1000 BCE. Eventually, distilled spirits became commonplace in many civilizations.

Before the 1800s, most spirits produced in the United States were not aged in barrels. They were produced and consumed as clear spirits, as all distilled alcohol is clear before it is aged. People added sugar or dried fruit to the alcohol to give it flavor. Historians are unsure of when producers first started to age spirits in barrels in Kentucky, but the aging process was mentioned in a Lexington newspaper as early as 1826. By the end of the 1800s, alcohol production in Kentucky became more profitable as the railroads made moving goods easier and cheaper.

Overview

Whiskey is alcohol that is made from grain and aged in barrels. Much of the alcohol made through distillation is clear spirits (e.g., gin and vodka) that people can change by flavoring it. Whiskey is unique because it uses specific grains and is aged in wooden barrels. The alcohol develops a brown color and a unique flavor because of the barrel aging. Scotch whisky (made in Scotland), Canadian whisky, Irish whiskey, and Japanese whiskey are all unique because of the different ingredients and methods used to produce them. In the United States, distillers make American blended whiskey and various types of pure whiskey (including bourbon). American blended whiskey is made by blending aged whiskey with neutral, clear spirits. Producers then add coloring and flavoring to the whiskey to make it taste and appear more like all the alcohol was aged in barrels. This type of whiskey is generally less expensive than other types because half of it does not have to go through the time-consuming aging process. Bourbon is different from blended whiskey in that it is all aged in barrels. It is aged in new charred oak barrels, which gives it a dark color and a sweet flavor. Bourbon is also unique because it is made with at least 51 percent corn.

The process to create bourbon begins with choosing the ingredients that produce the alcohol. People use various amounts of corn, rye, wheat, and malted barley, which is made by soaking the grain in water and then drying it. Producers use different ingredients to create different flavors in their final products. For example, rye generally makes a whiskey spicier and less sweet, and wheat makes whiskey smoother but adds less flavor. Most recipes include malted barley because the enzymes in the grain help turn starch into sugar. Each whiskey producer chooses a mash bill, which is the mix of grains used to make the drink. The producer then adds water to the grains to make a mash. Most bourbons are made with a sour mash, which means a portion of mash from the last batch is reused. The producer sets out some leftover mash overnight, and adds more grains and water the next day. The sour mash helps begin the fermentation process in the mash. During fermentation, sugars are converted into alcohol by yeast.

The next step in the process is to remove the liquid mash from the grain. The liquid mash includes sugars. Next, the liquid mash is fermented. During fermentation, the sugars are broken down into alcohol by yeast. The product of this process is alcohol.

The liquid is then put into a still, where distillation separates the alcohol from the rest of the liquid. The resulting liquid is clear and high in alcohol. The producer usually adds water at this time to reduce the level of alcohol. The liquid is then put into barrels to age, where it will take on bourbon’s signature flavor and brown color. To be a true bourbon, the alcohol must age in new oak barrels that have been charred. Straight bourbon must also age for at least two years, though many types of bourbon age for at least five years. In general, the longer a bourbon ages, the more desirable it becomes. Aged bourbon is more expensive because of the time needed to produce it and because small amounts of alcohol evaporate during the aging process. The bourbon is bottled after it has aged. During the bottling process, the producer is not allowed to add anything other than water. Adding any flavoring or coloring would mean the drink was no longer real bourbon. The final product must be bottled at no less than eighty proof, while federal regulations limit the proof at which bourbon enters the barrel to no more than 125 proof.

Bourbon is similar to some other common types of whiskeys. Rye whiskey is made in a way similar to bourbon, but the mash is made with a majority of rye instead of a majority of corn. This difference in the grain gives the drink a spicier flavor. Tennessee whiskey is also made in a similar way, but it is filtered through charcoal, which gives it a smoother and sweeter flavor than bourbon.

Starting around 1990, the bourbon market in the United States began to expand as more Americans were purchasing and consuming bourbon. Niche distilleries and markets grew, and eventually the secondary market became almost as popular as the mainstream market. A secondary market is when products are sold not by the original manufacturer, but by a second party. Despite distilleries growing and producing more bourbon, some labels became harder to find and purchase because of secondary markets and subsequent mark-ups. According to a 2026 report from the Kentucky Distillers' Association, bourbon sales added $10.6 billion to the Kentucky economy during 2024–25. However, retaliatory tariffs imposed by Canada in 2025, in response to US tariffs on Canadian markets, significantly impacted the US whiskey industry, resulting in export declines and reduced sales into the mid-2020s. 

Bibliography

Albala, Ken. History of Bourbon. Audible Originals, 2019.

“Bourbon Market by Product (Traditional, Rye, Wheat), Application (Supermarkets, Independent Retailers, Convenience Stores, Online Sales), & Region for 2024-2031.” Verified Market Research, May 2025, www.verifiedmarketresearch.com/product/bourbon-market/. Accessed 17 Apr. 2026.

Clark, Mike, and Barry Kornstein. "The Economic and Fiscal Impacts of Kentucky's Distilling Industry, 2024–2025." Kentucky Distillers' Association, 2 Feb. 2026, kybourbon.com/wp-content/uploads/2026/02/FINAL-KDA-Economic-Impact-Report-2.2.26.pdf. Accessed 21 Apr. 2026.

Ettinger, Dylan. “What’s the Difference Between Bourbon and Whiskey?” Food & Wine, 14 May 2025, www.foodandwine.com/bourbon-and-whiskey-differences-11734282. Accessed 17 Apr. 2026.

Górak, Andrzej, and Eva Sorensen, editors. Distillation: Fundamentals and Principles. Elsevier, 2014.

McMahan, Dana. “Think Bourbon Has to Be Made in Kentucky? Think Again. Here’s the Truth.” Courier-Journal, 13 Jun. 2019, www.courier-journal.com/story/life/food/spirits/bourbon/2018/09/25/bourbon-does-not-have-made-kentucky/1410542002/. Accessed 17 Apr. 2026.

Schreiner, Bruce. “A Booming Bourbon Industry Has Kentucky Leaders Toasting Record Growth.” AP News, 7 February 2024, apnews.com/article/kentucky-bourbon-whiskey-record-growth-c6fecd8c74485354aca1f19301cb5bc8. Accessed 17 Apr. 2026.

Siemens, Shannan. “5 Rules That Make It Bourbon.” CNBC, 5 Jun. 2015, www.cnbc.com/2015/06/04/5-rules-that-make-it-bourbon.html. Accessed 17 Apr. 2026.

Verges, Virginia L., et al. Lab-Scale Methodology for New-Make Bourbon Whiskey Production. no. 3, Jan. 2023, pp. 457–57, doi:10.3390/foods12030457. Accessed 17 Apr. 2026.

“What Is Bourbon?” Bourbon Country, www.bourboncountry.com/all-about-bourbon/what-is-bourbon/. Accessed 17 Apr. 2026.