It's been a ongoing debate that's raged for centuries, but now scientists in Sweden believe they have found proof that whisky really does taste better with a dash of water.

The study, which looked into the effects of dilution on the flavours of whisky found that the taste of a dram is actually improved because it drives  the inherent flavour compounds to the surface.

The Swedish team claims they are able to show how alcohol interacts with a chemical key to whisky’s smoky taste, creating a naturally occurring organic compound guaiacol – which is also responsible for the flavour of smoke preserved food like bacon, fish and roast coffee – to be driven towards the bottom of a bottle, or glass.

However, a few drops of water helps to force the compound towards the surface giving the drinker “a fuller taste”.

Prof Bjorn Karlsson, a chemist at Linnaeus University, Kalmar and his colleagues said the taste of the chemical, and similar compounds, are enhanced when the spirit is diluted prior to bottling.

He added: “The taste of guaiacol and similar compounds will be more pronounced when whisky is further diluted in the glass.”

Prof Karlsson explained that  distilled malt whiskies typically contain around 70 per cent alcohol by volume before it is aged in barrels for at least three years.

Some alcohol evaporates during the maturation resulting in an alcohol content of around 55-65 per cent abv (cask strength whisky).

Before bottling, the whisky is diluted to around 40 per cent abv by the addition of water, which Prof Karlsson says “changes the taste significantly”.

The Swedish scientist added: “Whisky enthusiasts often also add a few drops of water to the spirit before drinking in order to further enhance the taste. Apart from water and alcohols, whiskies contain different organic compounds that contribute to their taste.

“Many whiskies, especially those that are made on the Scottish island of Islay, have a typical smoky taste that develops when malted barley is smoked on peat fire.

“Chemically, the smoky flavour is attributed to phenols, and in particular guaiacol, which is much more common in Scottish whiskies than in American or Irish ones.”

In the study Prof Karlsson and colleague Prof Ran Friedman carried out computer simulations of mixtures of water and pure alcohol, or ethanol, in the presence of guaiacol.

At concentrations of alcohol up to 45 per cent, guaicol was more likely to be present at the surface of the liquid, rather than in the bulk.

Prof Karlsson said: “In a glass of whisky it will therefore contributes to both the smell and taste of the spirit.”

The findings by Prof Karlsson and Prof Friedman, which are published in Scientific Reports, suggest they have been right all along – and could also have implications for gin, rum and brandy.

But they said deciding how much water you then add is a matter of personal taste.

Prof Karlsson added: “Overall, there is a fine balance between diluting the whisky to taste and diluting the whisky to waste.

“This balance will depend on the concentration and types of taste compounds that are characteristic for each whisky. Similar considerations can be used to optimise the alcohol concentration of other spirits including gin, rum and brandy.”

A spokeswoman for the Scotch Whisky Association said: “Taste is one aspect of flavour. More broadly, flavour is largely perceived by aroma.

“The addition of water tends to increase the volatility of aroma compounds as they tend to be more ethanol soluble than water soluble.

“So it is easier to perceive the aroma compounds in the ‘headspace’ above the whisky when water is added as they become less soluble and are driven out of the liquid.

“The other factor is that reducing alcohol strength or increasing water concentration reduces the alcohol sensation on the nose and tongue, which would otherwise mask the more subtle aroma compounds.”

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