Analysis of Barrel-Aged Kentucky Bourbon Whiskey by Ultrahigh Resolution Mass Spectrometry

In an effort to characterize differently aged bourbons and to determine whether bourbons could be “fingerprinted” by their chemical compositions, we used Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) to characterize 2 distinct sets of bourbon samples. The first set of bourbons were prepared using the same mash bill but were aged differently (unaged (0 years), 2 years, 4 years, and 6 years) in oak barrels. The results showed an increase in the number of chemical compounds present as the bourbon ages. Most of the large changes in chemical composition occur in the first 2 years of aging. We also analyzed single barrel bourbons, which were produced identically but maturated in different, adjacent barrels, and the results suggested that significant differences exist among these samples. These results suggest that “fingerprinting” of different bourbons for authentication purposes may be complicated and that careful analyses, coupled with more comprehensive identification of chemical compounds in bourbons, are needed.