The basics of distillation
By BRYCE T. BAUER
This sidebar is a supplement to Rum’s Revenge
Without distillation, the highest alcoholic content of any beverage would top out in about the high teens, the point at which the yeasts stop producing alcohol. To achieve higher alcohol content, such as the forty percent — or 80 proof — considered standard for liquor today, the alcohol must be separated from all the other components, primarily water. Distillers do that by exploiting the difference between the boiling points of ethanol (the drinking alcohol) and water. When they heat up whatever fermented liquid they are using — called the mash or the wash — the ethanol boils off first, forming a vapor. The vapor flows out of the top of the still and is sent to the copper coils that give distilleries their iconic aesthetic. In these coils, the ethanol vapors cool and re-condense. That liquid isn’t pure ethanol—in fact, far from it. Distillers often have to run that liquid back through the still to achieve the desired alcohol concentration. But for pretty much any alcoholic beverage other than vodka, the distiller doesn’t want to produce too pure a product—those “impurities” carried over with the ethanol during distillation are what give a liquor some of its signature flavors.