LIFESTYLE
DOES adding water to whiskey really make it taste better?
Bjorn Karlsson and Ran Friedman of the Linnaeus University Centre for Biomaterials Chemistry are not whiskey drinkers, but Friedman visited Scotland and he raised an eyebrow at the locals’ dedication to watering down even the fanciest Scotch.
Like a good scientist, he wanted to test the assumption, so he teamed up with Karlsson and used computer simulations to model the molecular composition of whiskey.
There were two competing theories for why adding water to whiskey might improve the flavour, Karlsson said. The first suggests that adding water traps compounds that are unpleasant.
Whiskey contains fatty acid esters that have two very different ends. The head is electrostatically attracted to water and the tail is not.
Fatty acid esters in water can form compounds called micelles. In micelles, all the tails come together in the middle while the heads form a sphere on the outside, like a bouquet of lollipops with their sticks all tied together on the inside. Adding water to whiskey could, theoretically, cause more micelles to form, trapping compounds that don’t taste or smell good.
A competing theory suggests that adding water releases molecules that improve the flavour. Water and ethanol don’t make for a perfectly uniform mixture.
Aromatic compounds could become trapped in ethanol clusters and never reach the surface. Our tongues are only capable of identifying the flavours sweet, salty, sour, bitter and umami (savoury), so aroma is really important for detecting all the other flavours that connoisseurs appreciate in whiskey.
Focus
Karlsson and Friedman found that fatty acid esters exist in such low concentrations that the first theory was unlikely, so they decided to focus on the second. In reality, “whiskey is a complicated mixture of hundreds or even thousands of compounds”, Karlsson said. They focused on just three: water, ethanol and an aromatic compound called guaiacol.
Guaiacol is what gives whiskey that smoky, spicy, peaty flavour. Chemically, guaiacol is similar to a lot of other whiskey aroma compounds like vanillin (with the scent of vanilla) and limonene (citrus).
These and other flavour compounds are not attracted to water and are more likely to become trapped in ethanol clusters.
“Adding water changes the equilibrium,” said Daniel Lacks, who was not involved with the study, but conducts similar modelling experiments at Case Western University.
The new model shows that diluting the whiskey “causes molecules to rise to the surface”.
But Paul Hughes, a food scientist and distilling expert at Oregon State, was not convinced that the propensity of ethanol to rise to the surface when whiskey was diluted told the whole story.
In the simulation, only three types of molecules were included and their activity was modelled in a very tiny volume of spirits.
“My sense is that the box they’ve used isn’t tall enough,” Hughes said. – The Washington Post