The 3S,4S isomer (cis-3-Methyl-4-octanolide), commonly known as whisky lactone or quercus lactone is an important ingredient in the aroma of whiskey (where it was first identified by Suomalainen and Nykänen in 1970),and other alcoholic beverages that have been aged in oak barrels. It is sometimes added to the liquor as a flavoring agent. It has a coconut, celery or fresh wood aroma, that can be detected by humans at the concentration of 1 μg/L in air. A mixture of the cis and trans isomers is repellent for mosquitos and flies.
Lactones contribute significantly to the flavor of fruit, and of unfermented and fermented dairy products, and are therefore used as flavors and fragrances. Some examples are γ-decalactone (4-decanolide), which has a characteristic peach flavor; δ-decalactone (5-decanolide), which has a creamy coconut/peach flavour; γ-dodecalactone (4-dodecanolide), which also has a coconut/fruity flavor, a description which also fits γ-octalactone (4-octanolide), although it also has a herbaceous character; γ-nonalactone, which has an intense coconut flavor of this series, despite not occurring in coconut, and γ-undecalactone.