I know you can look up the answer on Wikipedia, but I thought I’d look back in time a bit to find some explanations that are a minimum of fifty years old. Why? because I like to know how things used to be done.
Rye whiskey is made from rye and malt, and depending on the recipe (“mash bill”) smaller amounts of other grains, including wheat and corn. The addition of other grains in addition to rye appears to be a more recent addition to the standard recipe. The process begins with grinding the grains separately from the malt. After grinding, the grains are placed into a mash tank.
The next step is to prepare the malt. Barley is kept between 50 and 60 degrees and steeped in water until it sprouts. After 10 to 14 days the roots should grow between 1/2 to 1 inches long. It is then kept moist and at a temperature less than 60 degrees and aerated until the sprouts develop. It is then heated to no more than 140 to 158 degrees and 2 to 3 percent moisture. The resulting product is called “maltose.” After this roasting, the maltose is ground in preparation for adding it to the mash. The maltose contains enzymes which convert the unfermentable grain starch (from the rye and other grains) into fermentable sugar. Even at no more than 10% it can convert all of the starch in the unmalted grains.
Once inside the mash tank the unmalted mash is cooked by forcing steam up through the mash from the bottom of the tank. It is then cooled with cold water circulating inside coils. When cooled, the ground malt is added and the mixture is agitated. This converts the grain starch into fermentable sugar. The mash is then pumped through cooling pipes. This mash is now “distiller’s beer.” This is pumped into the still. The still separates the alcohol from the beer and it rises out of the top of the still into the condenser. Cold water is pumped into a jacket around the condenser which cools the vapor and creates “new whisky,” which is 100 to 120 proof. This new whiskey is aged in charred white oak barrels. The charred liner absorbs impurities.
How is Rye different from Bourbon, Gin or Scotch?
Bourbon whiskey is made the same way, except that the main ingredient is corn with a small portion of rye. The final proof is no more than 160 or it becomes “corn whiskey.”
Gin is made of the same materials and in the same manner as well, with one addition; juniper berries are boiled in the last distillation, imparting their peculiar flavor.
Scotch is whisky made in Scotland and substitutes barley for rye. A peat or smoky flavor is imparted by roasting the malt over peat fires.
Current Requirements: Departing from historical sources, the requirements for the different American whiskeys are as follows:
27 CFR § 5.22(b)(1)(i) “Bourbon whisky”, “rye whisky”, “wheat whisky”, “malt whisky”, or “rye malt whisky” is whisky produced at not exceeding 160° proof from a fermented mash of not less than 51 percent corn, rye, wheat, malted barley, or malted rye grain, respectively, and stored at not more than 125° proof in charred new oak containers; and also includes mixtures of such whiskies of the same type.
- Rye Whiskey: 51%+ rye grain, less than 160 proof, poured into new charred oak containers at 125 proof.
- Bourbon Whiskey: 51%+ corn, made in the U.S., less than 160 proof, and poured into new charred oak containers at 125 proof.
If the whiskey stays in the barrel for at least two years, it can qualify as a “straight” whiskey, though this is a term rarely sought after by producers.
If the whiskey is made outside of the U.S. it cannot be called “bourbon” here in the U.S.
If the whiskey is made in Tennessee, it can be called “Tennessee Whiskey” regardless of whether it is run through the “Tennessee Process.”