Wood Smoke and Charred Wood

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.