As any whisky enthusiast will tell you, adding a drop of water to your dram improves the smell and flavor of the drink. Using slightly unconventional computer simulations, scientists have been able to explain exactly why this works.
Björn Karlsson, co-author of the study, explains that “the taste of whisky is primarily linked to so-called amphipathic molecules, which are made up of hydrophobic and hydrophilic parts.” In other words, one side of the “taste” molecule found in whisky is attracted to water, while the other is repelled by it. This molecule, known as guaiacol, has a major bearing on the alcohol’s flavor.
Guaiacol is commonly found in smoky and peaty Scottish whiskies, and has been identified as the cause of the distinctive flavor that is loved by whisky connoisseurs all over the world. By using computer simulations of ethanol and water mixtures with guaiacol added, the researchers were able to observe how different concentrations of the two liquids changed the behavior of the flavor molecules.
They concluded that guaiacol is more likely to bind to the alcohol molecules. When the alcohol concentration is around 70%, as it is when first barreled, these molecules, with the guaiacol attached, tend to gather somewhere around the middle of the liquid, essential preventing the flavor from rising to the surface.
As more water is added, such as during bottling, when the concentration is reduced to around 45%, the alcohol molecules spread out more, meaning that more of the guaiacol floats to the surface.
Ran Friedman, who was another co-author of the study, explains, “this suggests that in a glass of whisky, guaiacol will therefore be found near the surface of the liquid, where it contributes to both the smell and taste of the spirit.” However, they found that this effect does not stop there – if the whisky is diluted down to 27%, there is an increase of guaiacol at the liquid-air interface.
This results in a more superior flavor, something that all whisky enthusiasts will know about. While diluting a good whisky down to 27% may seem low, some whisky drinks are known to dilute it as much as 20%.