On Food and Cooking

the barrel as well as matured there after
fermentation, and develop a distinctive
barrel-fermented flavor. One unusual
component of that flavor, produced by the
action of yeast enzymes on compounds
found in toasted oak, is a sulfur-containing
chemical whose aroma is reminiscent of
roasted coffee and roasted meat
(furfurylthiol).
Alternatives to Barrels Oak barrels are
expensive, so only relatively expensive wines
and spirits are aged in them. There are other
ways of getting oak flavor into less expensive
products. Boisés, extracts made by boiling
wood chips in water, are a traditional
finishing additive in French brandies,
including Cognac and Armagnac. In recent
years, large-volume winemakers have begun
putting barrel staves, oak chips, and even
sawdust into wines while they mature in
containers made of steel and other inert
materials.