The Science Of Whiskey
September 9, 2013

The Science Of Whiskey

Michael Harper for - Your Universe Online

Bourbon and rye whiskeys are more than just the sum of their parts. While each flavor combines to make a distinct and finished product, the individual components remain, playing crucial roles in the distinct flavor of the end product.

Scientists, researchers and distillers have long been breaking down these spirits to determine the chemical compounds and flavor profiles of each one, resulting in a study now known as the “chemistry of brown spirits.”

As the art of distilling becomes increasingly popular, researchers and enthusiasts from the University of California-Davis Food Safety and Measurement Facility say they’re getting closer to understanding the chemical fingerprint of these brown spirits.

Dr. Thomas Collins, research director at the UC-Davis presented his findings at the 246th National Meeting & Exposition of the American Chemical Society in Indiana. According to Collins, understanding the chemical makeup of brown spirits is less about understanding the taste and more about creating a superior product every time.

“Whiskeys’ chemical profiles could be used for distillers’ quality assurance or process improvement programs,” explained Dr. Collins in a press statement. "In addition to that, they could be used to help speed up production. I think many of the small distilleries - the craft distilleries that are cropping up - may be interested in doing that."

"It's difficult to get a whiskey business going when you typically need to age the product for three or four years or longer. Another application of our broader project that includes international whiskeys could be helping manage counterfeit and fraud, which is a huge issue for expensive scotches that are exported from Scotland to customers all over the world."

After pouring a shot of whiskey for sampling, Dr. Collins and team found hundreds of nonvolatile compounds - chemical compounds that remain in the spirit and do not evaporate. This means each shot of whiskey contains its own symphony of flavors that the distiller must finesse into a unified yet multi-layered experience.

When other samples were introduced, the researchers found as many as 4,000 individual nonvolatile compounds. Many of these compounds mingled with one another and created compounds, giving the spirit that distinct aged and mellow flavor.

Though individual and distinct spirits, bourbon, whiskey and rye share some crucial similarities. For instance, a bourbon is a whiskey which contains at least 51 percent corn. The rest of the grain bill is filled out with either barley, wheat or rye. Scotch contains more barley. Rye whiskey, as the name implies, is distilled with more rye than barley or corn.

When distilled, a whiskey must come in at 160 proof or less and when put into a barrel to age, it must be equal to or less than 125 proof. Most often, the barrel of choice is oak, a dense wood containing many flavor compounds which are slowly released into the liquid.

Even though different whiskeys can be distilled in America, they’re processed differently.

Tennessee whiskey, for instance, is filtered through sugar maple charcoal, unlike bourbon.

According to Dr. Collins’ research, each of these ingredients — the grain mixture, the barrel and of course, time — can add their own crucial flavor compounds to shape the overall flavor of the spirit. His research distinguished a chemical difference between Tennessee whiskey and bourbon, not at all unsurprising given the different ways that they’re distilled.

What is surprising, however, is that even though bourbons and rye whiskeys contain different ingredients, when distilled in the same facility they more closely resembled one another chemically than two spirits distilled in separate buildings.