Look away, whisky purists! A dram is better with water

IT is an age-old debate among those partial to a wee dram.

But scientists say whisky really is better with a dash of water than neat.

The taste of the spirit is improved by dilution as it drives flavour compounds to the surface, the study found.

A Swedish team has shown how alcohol interacts with a chemical key to whisky’s smoky taste. It causes guaiacol – also responsible for the smoky flavour of bacon and roast coffee – to be driven towards the bottom of a bottle or glass.

A few drops of water forces it back towards the top.

Professor Bjorn Karlsson and his team said the taste of the chemical, and similar compounds, are enhanced when the spirit 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.’

Professor Karlsson, a chemist at Linnaeus University, said the spirit’s distinctive taste is produced is by the distillation of fermented grains, ageing – and dilution.

Distilled malt whisky typically contains around 70 per cent alcohol by volume before it is aged.

Some alcohol evaporates during maturation, resulting in an alcohol content of 55-65 per cent. Before bottling, the whisky is diluted to around 40 per cent with water, which ‘changes the taste significantly’, Professor Karlsson said. He added: ‘Many whiskies, especially those made on the 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 American or Irish ones.’

He added: ‘There’s a fine balance between diluting whisky to taste and diluting whisky to waste.’

The findings were published in the journal Scientific Reports.

The Scotch Whisky Association said: ‘Flavour is largely perceived by aroma. The addition of water tends to increase the volatility of aroma compounds. So it is easier to perceive the aroma compounds in the “head space” above the whisky when water is added.

‘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.’