Scientists have identified that a single whiskey sample contains hundreds of nonvolatile compounds.

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.
Source-ANI