Aldehydes are part of the flavor profile of whiskey and other distilled beverages. Acetaldehyde is a feature in many whiskies, representing a large percentage of the total aldehyde content. It originates from the fermentation process, and though some is lost in the ‘foreshots’ during the distillation process, some remains, and adds a pungent, sharp note to the taste.
Other aldehydes originate, as with the whisky lactones, from the oak barrels in which the whisky is matured. Syringaldehyde gives a spicy, smoky note, with furfural providing an almond-like, grainy flavour. More familiar is vanillin, the compound that also gives vanilla its aroma. Bourbons are particularly noted for their vanillin content; new casks are used for the ageing of each batch of bourbon, as the vanillin content of the wood is much lower after one ageing cycle. Other aldehydes from the wood include coniferaldehyde and sinapaldehyde.
Additionally, some simpler aldehydes such as hexanal can contribute a grassy note in some whiskies, whilst a malty flavour is associated with 2- and 3-methylbutanal.
An aldehyde /ˈældɪhaɪd/ or alkanal is an organic compound containing a functional group with the structure −CHO, consisting of a carbonyl center (a carbon double-bonded to oxygen) with the carbon atom also bonded to hydrogen and to an R group, which is any generic alkyl or side chain. The group - without R - is the aldehyde group, also known as the formyl group. Aldehydes are common in organic chemistry.