Tennessee Whiskey is unique because it's made in the Volunteer State. Bourbon County water leads to distinctive bourbon. A distiller will always argue that some purportedly inimitable aspect of their process makes their product better than others.
It seems researchers at UC Davis may agree with them.
Bringing the nature versus nurture debate to the world of whiskey, the UC Davis team, led by Tom Collins (let the puns begin), research director at the Food Safety and Measurement Facility, presented a study at the September 9th National Meeting & Exposition of the American Chemical Society which finds that the main characteristics of American whiskeys are determined by the environment in which they were made, not their base ingredients.
In theory, at least, one may make bourbon that tastes surprisingly like rye.
It seems counter-intuitive. Isn't the main difference between bourbon and rye simply that bourbon is made with corn, while rye is made with rye? And aren't these differences vast? Rye imparts a spicier, fruitier flavor. Bourbon offers a smoother, sweeter flavor from its corn and usually longer cask aging. It seems pretty simple. Bourbon is bourbon, rye is rye, and the two shall never meet.
Regulations defining the different classes of spirits reinforce this impression. Whiskeys are a group of alcoholic beverages made by distilling fermented mash from grains such as barley, rye, corn and wheat. The Alcohol and Tobacco Tax and Trade Bureau defines bourbon as a whiskey "produced in the U.S., at not exceeding 80% alcohol by volume (160 proof) from a ferment mash of not less than 51 percent corn and stored at no more than 62.5% alcohol by volume (125 proof) in charred new oak containers." The rest of the grain bill may be filled out with barley, wheat or rye. Rye is labeled in much the same manner, except that it must be 51 percent rye, and without the requirement that it be made in the U.S.
Distillers themselves add to the confusion simply by using terms like "Kentucky Bourbon" and "Tennessee Whiskey." Legally speaking at least, Tennessee Whiskey is bourbon, despite the fact that makers such as Jack Daniels brand their product as Tennessee Whiskey. Although Kentucky whiskey distilleries use of water filtered by the limestone shelf in Bourbon County may add to the allure of Kentucky bourbon, federal regulations do not stipulate what water must be used to make bourbon.
In fact, the only government recognition of Tennessee Whiskey's special status is contained in the North American Free Trade Agreement (NAFTA). Most likely thanks to industry lobbying, NAFTA includes a section protecting the industry against knockoffs. Annex 313 defines Tennessee Whiskey as a "straight Bourbon Whiskey authorized to be produced only in the State of Tennessee." Under NAFTA, both Canada and Mexico agreed to prohibit the sales of counterfeit Tennessee Whiskey (note there also are similar protections for tequila and Canadian Whisky).
The UC Davis research team provides evidence that could be used to support these industry distinctions. Dr. Collins and his team found that, in many cases the key factor in determining a whiskey's flavor is not what grain is in the bottle, but where the spirit was produced ' and what other whiskeys are made at the distillery.
The researchers set out to determine the chemical differences among 60 different whiskeys: 38 straight bourbon whiskeys, 10 rye whiskeys, five Tennessee whiskeys and seven other American whiskeys, varying in age from two-to-15 years old. They found over 4,000 different non-volatile compounds across the different samples.
While researchers found a fair amount of overlap between the thousands of chemical compounds in the different spirits, they also found 50 to 100 chemical compounds such as fatty acids, tannins and even turpentine from the wood barrels, that can be used to distinguish a Tennessee whiskey from a bourbon to such an extent that Dr. Collins can tell the difference between them without tasting either. Their most surprising conclusion 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. In contrast, the ryes made at operations that do not also produce bourbon had a unique flavor profile distinct from corn whiskeys.
In other words, each distillery left a stronger fingerprint on the spirit's character than the grain did.
Dr. Collins is not sure why this is the case, but he thinks a big reason is that the dominating flavors in American whiskeys come from the wood, not the grains or the yeast. His team has yet to embark on the next step of their experiments'relating the differences in chemical makeup to potential sensory differences in aroma and flavor'but he feels fairly confident that the two are related.
From a business standpoint, these chemical profiles, or fingerprints, could potentially be used for quality assurance purposes, intellectual property protections, process improvement programs and even speeding up production, which may be of interest to many small and craft distilleries. One key barrier to entering the whiskey market is the need to age the product for three or four years or longer.
Dr. Collin's research suggests that the magical, perfect whiskey distillers and aficionados alike crave may not be so elusive. Distillers will just need to identify their preferred chemical profile. Until that happens, however, I happily volunteer my free tasting services to assist any whisk(e)y distiller improve their product.