Decanter Godinger with Glasses on Table

It has long been the practice of whiskey connoisseurs to add a few drops of water to their drink before they imbibed, so as to maximize the flavor profile of the spirit. Finally, a new scientific study offers evidence to explain why this practice actually is effective.

The study, by Björn C. G. Karlsson &  Ran Friedman, found that the presence of guaiacol is what makes whiskey with added water taste better. Karlsson and Friedman carried out computer simulations of water, alcohol and the organic compounds associated with the flavor of whiskey. Many of these molecules are referred to as amphipathic molecules, which have both water-repelling and water-attracting regions. One of these small-amphipathic molecules that they focused on is called guaiacol.

The researchers looked at both bottled and cask-strength whiskey. Bottled whiskey has been diluted to about 40% alcohol by volume, down from 70% after distilling. Cask whiskey is stronger, at about 55% to 65% alcohol by volume.

When the computer models diluted whiskey to just 45% alcohol, guaiacol was more likely to be present at the surface of the whiskey than in the rest of the liquid. This means that guaiacol heavily contributes to both the smell and taste of the spirit. That’s why whiskey with added water tastes better: The taste molecules are at the top of your glass.

It is interesting to note that at concentrations of alcohol above 59%, guaiacol was not nearly as present at the surface of the whiskey.

Ran Friedman spoke about the study in a recent email to CNN, saying that

“From a molecular perspective, water and alcohol don’t completely mix. Instead, we have clusters of water molecules and clusters of alcohol molecules. When whisky is diluted, the alcohol is driven to the surface, and many of the taste molecules follow it because they like to be in a slightly less aqueous environment. The taste that we experience is therefore enhanced — but there’s a limit. If we dilute the whisky too much the concentration of the taste compounds is reduced and the drink will be meager.”

So there you have it, your friends that insist on adding water to their whiskey may be snobs, but they do have science to back it up. If you have never tried it before, next time you’re indulging try adding a few drops of water to your cask-strength drink.