The essential terms, legal requirements, and production process behind America's native spirit.
- Bourbon
- American whiskey made from at least 51% corn, distilled to no more than 160 proof, aged in new charred oak containers, entered at no more than 125 proof, bottled at minimum 80 proof. Must be produced in the USA.
- Straight Bourbon
- Bourbon aged at least 2 years with no added coloring, flavoring, or blending with other spirits. If under 4 years, an age statement is required.
- Mash Bill
- The grain recipe. Bourbon requires 51%+ corn; the balance is rye, wheat, or malted barley. High-rye mashes produce spicier whiskey; wheat substitution yields softer, sweeter profiles.
- Sour Mash
- A portion of spent mash (backset) from a previous distillation is added to the new fermentation, controlling pH and flavor continuity batch to batch. Nearly universal in bourbon production.
- Wheated Bourbon
- Wheat replaces rye as the secondary grain. Produces a softer, sweeter whiskey. Famous examples: Maker's Mark, W.L. Weller, Pappy Van Winkle.
- Bottled-in-Bond
- A 1897 federal standard: straight whiskey from a single distillery, single distillation season, aged minimum 4 years in a federally bonded warehouse, bottled at exactly 100 proof.
- Barrel Proof / Cask Strength
- Bottled at the natural barrel concentration without dilution. Higher proof, more intense flavor. ABV varies barrel to barrel.
- Single Barrel
- Each bottle comes from one individual barrel rather than a blend. Natural variation exists between barrels from the same distillery and year.
- Small Batch
- No legal definition. A marketing term generally indicating a blend of a limited number of select barrels, as opposed to large-scale production blending.
- Angel's Share
- Whiskey lost to evaporation during aging. In Kentucky's climate of hot summers and cold winters, this can reach 3–5% per year — a significant loss on long-aged barrels.
- Tennessee Whiskey
- Meets all bourbon requirements but is additionally filtered through sugar maple charcoal before aging (the Lincoln County Process). Jack Daniel's is the most famous example.
- Rye Whiskey
- Made from at least 51% rye grain. Spicier and drier than bourbon. Historically dominant before Prohibition; now experiencing a major revival.
- Age Statement
- The age on the label reflects the youngest whiskey in the bottle. No age statement (NAS) typically means under 4 years for straight whiskey.
- New Charred Oak
- Bourbon must age in new, charred oak containers. The char layer acts as a carbon filter and caramelizes wood sugars that impart vanilla, caramel, and spice notes.
1
- Grain Selection & Milling
- Corn, rye or wheat, and malted barley are selected per the distillery's mash bill recipe, then ground into a coarse meal.
2
- Cooking & Mashing
- Grains are cooked with water at different temperatures to convert starches into fermentable sugars. Sour mash backset is added to control pH and ensure consistency.
3
- Fermentation
- Yeast is added to the cooled mash and ferments for 3–7 days, producing a low-alcohol liquid called distiller's beer at roughly 8–10% ABV.
4
- Distillation
- The beer is run through a column still (beer still), stripping alcohol to ~65% ABV. A doubler or thumper then refines it further — to a maximum of 160 proof by law.
5
- Barreling
- New charred white oak barrels (typically 53 gallons) are filled at no more than 125 proof and moved into multi-story rickhouses for aging.
6
- Aging
- Kentucky's climate does the work — summer heat drives whiskey deep into the wood; winter cold pulls it back. Each cycle extracts color, flavor, and the char's natural filtering. Minimum 2 years for Straight Bourbon.
7
- Bottling
- The master distiller selects and blends barrels, proofs down to bottling strength with pure water, and the whiskey is filtered, bottled, and labeled.