Designation (also lactones) for inner esters of oxycarboxylic acids with a strong, usually pleasant odor; in the case of higher-quality esters, often after musk or coconut Lactones play a very important role among the volatile aromatic substances in wine, especially the g-lactones. According to their origin, the oak, they are also called "Oak-Lactones", or according to their appearance "Whisky-Lactones". Lactones are already formed in the grapes or during fermentation, as well as during the toasting of oak wood by breaking down the lipids. Especially in oaks from the French Allier region or from America, they or the precursor are contained to a larger extent. In contrast to other substances such as furfurals, they are found in smaller quantities in burnt wood. The substance sotolone, which is found in botrytis wines and oxidatively aged wines such as Madeira, Rancio and Sherry, also belongs to the lactones. See also under toast aroma.