Water’s Importance in Alcohol Distillation
Water plays a pivotal role in whiskey distillation. It’s used in malting processes, for diluting before bottling (except cask strength releases) and driving steam-power distillation stills – as well as having indirect influences such as temperature.
Water’s chemical composition has an enormous influence on the flavor of finished whiskey, which explains why so many distilleries are located near rivers or lakes whose quality of water largely determines which whiskey varieties they produce.
Fractional distillation is a key feature of any distillation system, as it enables higher concentrations of alcohol to be extracted from wash. By splitting liquid and vapor at different temperatures, fractional distillation enables this separation process to take place and allows extraction at higher concentrations than would otherwise be possible without this technique.
The initial vapors produced from a wash have the highest alcohol concentration. These are known as the heads and contain low boiling point alcohols, fusel compounds, aldehydes, acetone and other volatile compounds with unpleasant tasting and potentially toxic concentrations that should not be drunk directly.
Heads smell similar to nail polish remover and should usually be cut away and sent down the next run to be redistilled, while hearts have higher concentrations of alcohol and can be enjoyed directly.