FOR hundreds of years, it has been the process which gives whiskies their unique aroma, body and taste although nobody is exactly sure how.

But now scientists from Heriot-Watt University in Edinburgh are working with whisky giant Diageo to quantify exactly how whisky gets its flavour from the cask during maturation.

Heriot-Watt University has assembled a team of experts for the project, which includes researchers from the International Centre for Brewing and Distilling (ICBD), but also scientists who specialise in chemistry, physics, machine learning and data science.

Enjoying our unrivalled business coverage and analysis? Make it official with a Herald subscription for only £1 for three months.
This offer ends Friday so click here and don't miss out!

The three-year Knowledge Transfer Partnership (KTP) will investigate various new analytical methods to get to the bottom of what goes on in a whisky barrel.

The scientists will use spectroscopic methods to identify the natural compounds and understand the chemistry of the process that imparts such distinctive and complex flavours to the maturing spirit.

This information will be coupled with sensory input such as visual inspection of newly-manufactured barrels and the evolving flavour and nose of the whisky.

Together it will be used to develop a data science platform that will demystify the process of maturation.

Read More: Scapa Distillery launches Orkney whisky tourism experience

Professor Annie Hill from Heriot-Watt’s ICBD said: “Producing a quality Scotch whisky is an art.

“The new KTP with Diageo is particularly exciting because it combines traditional and novel methods to generate ‘big data’ that may be used to further understand whisky maturation.

“The ability to more accurately predict the outcome of maturation based on the characteristics of the cask and new make spirit will enable significant improvements in inventory management and reduction of losses, leading to overall efficiencies in Scotch whisky production.”

Until now, no-one has been able to pin down scientifically about what exactly happens inside the cask.

Read More: The Macallan single malt Scotch whisky in deal for Jerez sherry casks

The maturation of a whisky takes place in three very essential steps through a complex chemical reactions described as additive, subtractive and interactive maturation.

During additive maturation, the distillate begins to draw flavours and colours from the wood which are then distributed throughout the liquid, and a large number of chemical compounds are formed.

In addition, during additive maturation, the whisky absorbs compounds from the liquid that was previously stored in the barrel, such as sherry.

After the whisky has built up a broad spectrum of aromas, subtractive maturation is about breaking down unwanted flavours.

The third area of maturation is the least fully understood and is called interactive maturation. This is where the peculiarity of the oak wood and the influence of the climate come into play.

During interactive maturation, gases enter and escape the cask and there is an exchange between the contents of the barrel and the environment through the barrel wall.

What enters or leaves is determined by temperature fluctuations and humidity, as well as the peculiarities of the warehouses and their location.

Matthew Crow, research partnerships manager with Diageo’s Global Technical team, said: “Scotch is matured for at least three years and often much longer, a process that enriches and refines its flavour.

Read More: Amber nectar goes green as whisky has a low carbon makeover

“However, a barrel’s potential for imparting flavour, and how the whisky will mature in that barrel, involves many complex factors.

“The industry, and Diageo in particular, have a long history of research across whisky production, and Heriot-Watt’s scientists will help us to take our understanding to a new scientific level.”

Professor Martin McCoustra is an expert on the interaction of chemical substances with complex surfaces and will be coordinating the cross-disciplinary team from Heriot-Watt University. He said: “We’ll start with simple optical and ultraviolet imaging of freshly-prepared barrels and then use infrared and optical spectroscopies to give us their chemical fingerprints.

“We’ll also use nuclear magnetic resonance, which is the laboratory equivalent of the MRI scan you would get in hospital, and mass spectrometry to trace how the chemical fingerprint of the spirit changes.

“These chemical fingerprints will include information on the natural compounds that contribute to the flavour of the maturing spirit. The skills of the coopers, distillers and blenders will give us a sensory evaluation of the barrel and evolving spirit.

“All this data will be used to train a machine learning system that will predict what the flavour quality of the whisky could be. This could significantly enhance whisky production, giving better data upon which to base fundamental decisions, such as how long a whisky should stay in a barrel.”