Vanillin, syringaldehyde, coniferaldehyde, sinapaldehyde, scopoletin, and ethanol lignin were found in both whiskey and neutral spirits aged in various types of white oak cooperage. Data obtained indicate that the mode of development of these congeners is similar for both whiskey and spirits, the amount formed depending upon the type of cooperage used and proof of distillate being aged. Experimental evidence was obtained which supports that from the literature in indicating that these aromatic congeners can arise from chemical reaction between the ethanol and components of the oak wood (charred or uncharred)-i.e., lignin-under the acidic conditions (pH 4 to 5) imposed by the barrel. The concentrations of other congener groups formed in both types of alcoholic products stored for 18 months in new charred barrels were similar.

Gas-liquid chromatography was utilized for the analysis of monosaccharides and glycerol in distilled spirits aged in new, charred white oak cooperage. Arabinose, xylose, fructose, glucose, galactose, and rhamnose were identified. Traces of fucose and mannose were indicated. Total concentration of sugars increased from 16 to 37 g/100 L at 100° proof and glycerol from 0.83 to 2.42 g/100 L at 100° proof during aging from 1 through 12 years. Compounds were identified by a comparison of GLC chromatograms of trimethylsilyl (TMS) ether derivatives, alditol acetates and trifluoroacetates, and TMS-aldono-l,4-lactones. Sugars and glycerol were quantitated as TMS ether derivatives with 3 % JXR organic phase on Gas-Chrom Q with an accuracy assessed at ±2—3%.