Surveying the Composition of Phenolic Compounds in Bourbon Barrel Staves
Jarrad Gollihue, Harlen Wheatley, and Seth DeBolt*
*University of Kentucky, N-318 Ag Sciences Center University of Kentucky, N-318 Ag Sciences Center University of Kentucky, KY 40546-0091 (firstname.lastname@example.org)
Bourbon whiskey is aged in new American white oak barrels that are charred. Charring of barrels produces a unique environment that the distillate interacts with from two to 23 years. The overarching hypothesis of this study is that the process of barrel charring disrupts the naturally occurring biopolymers in the wood and produces breakdown products that are desirable flavors. Here, we focused on the phenolic fraction of compounds found in the wood. This fraction consists of lignin, hydrolyzable tannin, and breakdown products formed during charring from cellulose and hemicellulose. The production of these breakdown products is highly variable in oak products. In this study, we surveyed lignin, tannin, total extractable phenolic compounds, and phenolic compounds in situ and how these values change from barrel charring and bourbon maturation. We furthered these analyses by looking at the interior, middle, and exterior subsec-tions of new and used barrel staves. Subsections of charred barrel staves indicate that phenolic and tannin content is higher in the interior of the barrel stave and decreases during maturation, while the lignin content was unchanged. Metha-nol extraction of the barrel interior subsection followed by GC-MS showed that compound profile and abundance shifts occur through the depth of the stave. To complete this analysis, the surface fraction of the charred interior was subjected to PYR-GC-MS, revealing even with the variation from stave to stave, some trends were found revealing a fingerprint of a flavor profile for each barrel surveyed.
Funding Support: NSF EPSCOR