What makes the flavour of each Single Malt Scotch Whisky unique?

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Professor from Stockholm University conducts research into how single malt Scotch whisky matures at Bruichladdich, Bowmore, Ardbeg and Kilchoman distilleries on Islay.

Otto Hermelin and Adam Hannett in a warehouse Bruichladdich

Prof Otto Hermelin of Stockholm University with Adam Hannett at Bruichladdich Distillery

Prof Hermelin says: "Using a mass spectrometer at the University, we monitor the changes in concentrations of substances such as esters over time and correlate these changes to the different conditions experienced by different casks."

There is more and more interest from around the world in the factors which affect the flavour of individual single malt Scotch whiskies, but to date there has been very little serious scientific research into why. All the spirit is made from barley and water and yeast - and is matured in oak casks – so why do the whiskies vary so much? Is it simply the distillery techniques – or does it have something to do with where the spirit spends its life maturing?

Someone was certain to rise to the challenge sooner or later and Otto Hermelin may have one of the world’s most coveted jobs. He is Associate Professor in the Department of Geological Sciences at the University of Stockholm. The whisky-loving professor has developed a program to monitor the maturation of spirit in four bonded warehouses at Bruichladdich, Kilchoman, Ardbeg and Bunnahabhain distilleries on the Hebridean island of Islay.

The program requires that each of these famous distilleries be visited on a regular basis and a series of samples taken back to Sweden for detailed analysis by the university mass spectrometer. It’s a tough assignment – but someone has to do it…

The question being asked is whether casks that spend ten years located up near the roof of the big distillery bonded warehouses, where the temperature and humidity is likely to fluctuate, will develop differently to casks that spend their lives slumbering at ground level? To check this, samples are drawn twice a year from casks located in different physical locations. All the casks were filled at the same time from the same batch of new-make spirit and into the same type of casks.

Sensors record the data at different positions and the information is then downloaded to computers every hour. The differential between the temperature and humidity levels at the top and bottom of these racks and also variations due to the physical location of the warehouses, is considerable.

The samples from the maturing whisky are taken to Stockholm University by Professor Hermelin and subject to detailed chemical and spectroscopic analysis of both organic and inorganic compounds and how these vary over time as the whisky matures. The research project is expected to last ten years.

The results could be of vital importance to the future of Scotland’s second biggest export industry. The law says that all Scotch whisky must be made and matured in Scotland – but does it matter where in Scotland this maturation occurs? If the character of a whisky is affected by its location within a single warehouse – then what about the location of the warehouse? If Scotch whisky has to be matured in Scotland, should Islay single malts always be matured on Islay?

Some in the industry argue that the location does indeed make a significant difference to the final character of the drink. For these distilleries, maturing at the place of origin is a not simply a badge of honour, it is an essential part of their being. Others claim that it makes no difference – and their spirit is shipped away to wherever is most convenient and expedient, which for a spirit distilled on Islay could mean a long stay in a warehouse located anywhere in the country and many hundreds of miles from the island where it was created.

The stakes are high in this multi-billion pound export industry. Provenance and the perception of provenance is vitally important – it is called Scotch whisky after all. The quietly spoken Swedish academic will not be publishing his painstakingly compiled report for many years to come, but it is sure to make interesting reading when he does.

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Lynton Davidson
Bruichladdich Distillery Co. Ltd
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Carl Reavey
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