Neither wood nor the smoke it gives off is an
herb or a spice, strictly speaking. Yet cooks
and makers of alcoholic liquids often use
burned or burning wood as flavoring agents —
in barbecuing meats, in barrel-aging wines
and spirits — and some of the flavors they
supply are identical to spice flavors: vanilla’s
vanillin, for example, and clove’s eugenol.
That’s because wood is strengthened with
masses of interlinked phenolic units, and high
heat breaks these masses apart into smaller
volatile phenolics (p. 390).
The Chemistry
of Burning Wood
Charred wood and smoke are products of the
incomplete combustion of organic materials
in the presence of limited oxygen and at the
relatively low temperatures of ordinary
burning (below 1,800ºF/1,000ºC). Complete
combustion would produce only odorless