lactones

are a group of phenols derived from oak that create many aromas, flavors, and textures in barrel-aged spirits. These include complex milky or coconut notes, vanilla, balsam, wood, pastries, earthiness, apricot, peach, leather, spices, green walnuts, and fresh herbs.The impact of phenols includes their transformation during barrel heating and/or burning, as well as the interactions with spirit in the presence of oxygen. Thus phenol effects can include “browning,” or oxygenation of the phenols; Maillard reactions, in which sugars and amino acids react or transform due to heat; methyloctalactones, or “whisky lactones,” including toast or coconut aromas; cyclotene, or maple syrup, grilled, and roasted licorice aromas; maltoland isomaltol, giving aromas of burnt sugar and caramel (both cyclotene and maltol are at least partly responsible for the “toast” aroma in pastries and spirits); furanic aldehydes, with aromas of roasted almonds; furfurals, including aromas of sawdust, maple syrup, toast, toasted almonds, coffee, and caramel; and 5-methyl-furfural, which also offers roasted almond smells. Vanilla is a phenol aldehyde, which is another transformed phenol compound.

As much as phenolic influences can be altered during barrel aging by the condition of the wood and its heating, burning, and such, differing woods (including species of oak) offer differing phenolic and other compounds. American oak is described as containing two or three times more coconut than European oaks (as well as more cocoa and caramel), but some of this (especially the cocoa and caramel) is due to differences in barrel production methods.

See also phenol.

“Whiskey Lactone.” American Chemical Society. https://www.acs.org/content/acs/en/molecule-of-the-week/archive/w/whiskey-lactone.html (accessed March 27, 2021).

By: Doug FrostSee also phenol.