Don’t ever let people tease you for watering down your whiskey. If they’re true aficionados, they’ll know that adding a splash of water or a few cubes of ice to your drink will actually enhance its natural flavors. But how can something as flavorless as water make a barrel-aged scotch or bourbon taste even better? Chemists think they’ve found the answer.
As The Verge reports, researchers from the Linnæus University Centre for Biomaterials Chemistry in Sweden analyzed the molecular composition of whiskey in the presence of water. We already know that the molecule guaiacol is largely responsible for whiskey’s smoky taste and aroma. Guaiacol bonds to alcohol molecules, which means that in straight whiskey that guaiacol flavor will be fairly evenly distributed throughout the cask. Alcohol is repelled by water, and guaiacol partially so. That means when a splash of water is added to the beverage the alcohol gets pushed to the surface, dragging the guaiacol along with it. Concentrated at the top of the glass, the whiskey’s distinctive taste and scent is in the perfect position to be noticed by the drinker.
According to the team’s experiments, which they laid out in the journal Scientific Reports [PDF], whiskey that’s been diluted down to 40 percent to 45 percent alcohol content will start to show more guaiacol sloshing near the surface. Most commercial whiskey is already diluted before it's bottled, so the drink you order in a bar should fall within this range to begin with. Adding additional water or ice will boost the flavor-enhancing effect even further.
As for just how much water to add, the paper doesn’t specify. Whiskey lovers will just have to conduct some experiments of their own to see which ratios suit their palate.