How whiskey is made

Every whiskey starts as grain: corn, rye, wheat, barley or others. The mix of grains, called the mash bill, sets the base flavour.

• Corn brings sweetness
• Rye brings spice: pepper, mint, dill
• Wheat brings softness
• Malted barley brings the enzymes that turn starch into sugar, plus a biscuit or cereal note

Why It Matters

Two bourbons can taste very different because of the mash bill alone. A wheated bourbon swaps rye for wheat; a high rye bourbon uses more rye than usual.

The grain is ground and cooked in water to make a mash. Yeast is added and, over a few days, turns the sugars into alcohol, making a beer-like liquid called the wash or distiller's beer.

What Changes The Flavour

• The yeast strain: many distilleries guard their own
• Sour mash: starting each mash with some backset from the last run keeps every batch consistent
• Fermentation time: longer fermentation tends to give fruitier flavours

The wash is heated in a still. Alcohol boils before water, so the vapour is collected and condensed into a stronger spirit.

• Pot stills work one batch at a time and keep more flavour
• Column stills run continuously and are used for most bourbon and grain whisky
• A doubler or thumper often gives column-still spirit a second distillation

The distiller keeps the hearts of each run and cuts away the harsher heads and tails. What comes off the still is clear new make, or white dog.

Most of a whiskey's colour and much of its flavour comes from the barrel. What the barrel is made of, how it was burned inside and what it held before all change what ends up in your glass.

New Or Used Oak

Bourbon and American rye must go into new charred oak containers, used once. Scotch, Irish and Japanese whisky mostly age in barrels that held something before, often ex-bourbon barrels or sherry casks, which give a gentler oak flavour.

Char Levels

Barrels are set on fire inside. A longer burn makes a deeper char layer, which filters the spirit and adds caramel, vanilla and smoke notes.

• #1: about 15 seconds
• #2: about 30 seconds
• #3: about 35 seconds
• #4: about 55 seconds, called alligator char

Toasting is a slower, gentler heat used instead of or before charring.

Sizes

• Standard American barrel: 53 gallons, about 200 litres
• Hogshead: about 250 litres
• Butt or puncheon: about 500 litres
• Small barrels: 5 to 30 gallons

Smaller barrels put more wood against less whiskey, so flavour builds faster.

Wood And Seasoning

American white oak is the standard. French, Hungarian, Mizunara and Chinquapin oak each bring their own spice and texture. Casks seasoned with sherry, port, wine or rum leave fruit and sweetness behind.

Whiskey ages for years as it soaks into and out of the barrel wood with every change in temperature.

• Warm upper floors of a rickhouse age whiskey faster than cool lower floors
• Some is lost to evaporation each year: the angel's share
• Some stays soaked in the wood when the barrel is emptied: the devil's cut

Age On The Label

An age statement gives the age of the youngest whiskey in the bottle. Straight whiskey has aged at least two years; Bottled-in-Bond at least four.

Barrels are chosen and blended into a batch, or bottled one barrel at a time.

• Single barrel: every bottle from one barrel
• Small batch: a blend of a relatively small number of barrels
• Water is usually added to bring the whiskey to bottling proof, unless it is barrel proof
• It may be chill filtered so it stays clear when cold

Some whiskeys spend extra time in a second cask before bottling, to add flavour.

• Sherry casks: dried fruit, nuts and spice
• Port and wine casks: red fruit and sweetness
• Rum casks: tropical fruit and molasses
• Beer casks: malt, coffee or hops

The label usually names the cask, such as "finished in port casks".