Secret behind characters of whiskey revealed

Every type of whiskey has a distinct chemical signature to match the complex combinations of grains, barrels, aging and other factors that makes it what it is.

Thomas Collins, Ph.D., and his team profiled 60 American whiskeys, which resulted in a treasure trove of information that could prove useful for whiskey-makers large and small as well as for regulators.

Using latest analytical tools, Collins' team found that a single whiskey sample can contain hundreds of nonvolatile compounds, the ones that tend to stay in the liquid rather than evaporate off.

Added up across multiple samples, the number of compounds comes to about 4,000 total, a scientific testament to the complex molecular mingling that occurs as a spirit ages, sometimes for decades, in a 53-gallon oak barrel.

Of the thousands of compounds in the resulting products, the scientists narrowed the field down to 50 to 100 contributors, including fatty acids, alcohols and tannins, comprising a spirit's signature that distinguishes a Tennessee whiskey from bourbon.

Though the ratios of grains used to make them differ significantly, bourbons and rye whiskeys made in the same distillery developed chemical signatures that looked more like each other than those of bourbons and rye whiskeys, respectively, of another producer.