How Barley Impacts Flavour, a Laddie Lesson in Science

Let’s start with the basics. Barley has always been of major interest for us. Every mash uses seven tonnes of it. And it has to come from somewhere, and be farmed by someone. Those places and people are the beginning of our whisky’s story.

In terms of raw ingredients, for single malt Scotch whisky, you’ve only got malted barley, yeast, and water to play with. Casks are not counted as an ingredient in the Scotch Whisky Regulations, they are a processing requirement rather than part of the recipe - we’ll come back to this.

Water is dictated by the sources available at the distillery’s location - our source water comes from our own reservoir, An Torran, and our bottling water is sourced from a spring that is situated just two miles from the distillery, on farmer James Brown’s land.  We use a mixture of two yeast strains which perform well with our longer fermentation times and give us consistency so we can explore the other variables, such as barley varietals.

We’ve made, and released, whiskies made from six-row heritage barley, we’ve made whiskies from two-row conventional barley from different locales. We’ve made whisky from the same locales but different harvests and cultivars. We’ve made whisky from farms that practise different farming systems – such as biodynamic and organic. And we’ve held onto a full reference library of samples, which leaves us little room for doubt that the differences are there.

Adam Hannett, our Master Blender, shared some two year old spirits from our Regional Trials in one of his early Festival Masterclasses. The same cultivar had been grown in The Black Isle, and in Aberdeen, in the same season. All batches were mashed, fermented and distilled in the exact same way. The spirits had been in first fill Bourbon barrels. Everyone present at the Festival could pick up the presence of vanilla notes which had come from 24+ months in the casks. But they also acknowledge that there were differences in the character, different emphases of aroma and flavour, in what they were tasting.

Esters and alcohols are the most abundant compounds present in new-make spirit. They’re a vital family of complex molecules which introduce an encyclopedia of flavours & aromas, including honey, pineapple and butterscotch. Most alcohols (primarily ethanol) are created during fermentation. The ethanol we collect during distillation adds to the texture of the spirit - another reason we prefer higher bottling strengths and don’t chill filter our whisky.

But there are also higher alcohols which each carry a distinctive aroma and flavour, which makes them members of a valuable class of molecules known in whisky-making as "congeners". They give the spirit fruity signatures and add to the oily texture. Hexanol, formed during malting thanks to barley’s natural enzymes, tastes grassy or citrusy.

The chemistry of malted barley is the foundation on which fermentation and distillation are built, the first step in the creation of a whisky's flavour. And the results are profound.

Barley is better for malting than many other cereals because of its layer of "living tissue" between the husk and the starchy interior. Some of the enzymes it produces break down the grain’s protein into amino acids - vital for the creation of the tasty alcohols and esters above. In wheat, rye, or corn, this living tissue is one cell thick. Barley’s is three cells thick, so much more powerful.

Barley also contains trapped phenolic acids. During mashing, these are released as ferulic acid, which yeast then converts into spicy, clove-like flavour compounds. 

Another transformation during malting occurs when the barley is kilned and roasted, changing its appearance and flavour, caramelising it. There's a lot of chemistry here involving the living tissue too, luckily, we have Lisa Matthews, Production Assistant, to explain what these compounds do:

“They act as antioxidants during fermentation and ageing. They also carry over directly into the whisky to influence the final colour and provide malty, toasty, or roasted flavour profiles.”

There have been scientific studies which have tried to quantify flavour. Some look at differences between cultivars, some at the differences from terroir and soils. See this Oregon State University study, or this research on wort (the liquid produced after mashing) destined for beer from the University of Adelaide.

Research into exactly how, and how significantly, the different levers you can pull regarding barley translate into different flavours in finished whisky continues. Professor James Brosnan, Director of Research at the Scotch Whisky Research Institute, kindly gave us the following opinion:

“As the starting raw material for malt whisky, barley (and how it interacts with the malting and distillery processes) is hugely influential at providing vital building blocks of flavour. But that does not automatically mean that every nuance or change in barley or its processing will cause a significant flavour impact in the bottle.”

Obviously, any locale’s individual harvest will also be a response to the conditions of that particular year. There seems to be a consensus that weather and environmental factors can affect the quality of the grain. And many think that ultimately quality should be measured only by how high the yield is, before any other variables.

Our approach is fundamentally different.

We’ve been deliberately exploring barleys that don’t fit this mould, and alternative agricultural methods. So as to release more flavours, more aromas, more potential. Much of this experimentation can be found in our single malts today.

Bere barley is a heritage grain grown in Orkney, which has very different genetics to modern barley varietals. Its kernels are much smaller and tougher to malt. They grow in rows of six rather than two. They prefer harsher maritime climates and lower quality soils. But most importantly, it contains higher fats, adding to the thickness of the mouthfeel found and loved in our Bere Barley releases.

It’s widely accepted in the scientific community that “environmental factors affect the biochemical components within the grain itself.” – University of California, Davis. Therefore, a change in the chemistry of the grain then affects all the chain reactions that take place during fermentation, which affects the compounds being distilled, which is then what goes into the barrels to mature and undergo further evolution.

We don’t have a full nutritional analysis of Islay-grown barley. But the data that we get back as routine from our Maltings partner shows that it, like Bere barley, has up to 25% higher protein content than barley grown on the mainland. According to Lisa, “It leads to a much more viscous spirit. The fruity congeners, that Bruichladdich is so well known for, come through much earlier in maturation, compared to Scottish Mainland barley, for example.”

Biodynamic and organic crops haven’t been fertilised with nitrogen, to accelerate their growth. Slower growth means a whole host of changes to their chemical identities. These farming methods don’t use pesticides. So the barley plants also have to come up with their own defences against insects. These natural defences again change the chemistry, producing more of those texture boosting long-chain molecules in the ethanol.

We are one of very few distilleries to have ever produced Biodynamic whisky, so there isn’t any objective analysis out there about what difference this type of barley makes to the flavour (yet). But, we’ve found it’s profoundly succulent, vibrant and intense.

To summarise the lesson today, in Lisa’s words:

“A spirit’s destiny is shaped long before it reaches the still. The choice of grain is critical, as the delicate precursors of its ultimate flavour profile are born in the soil and nurtured during the malting process.”

“Our passion at Bruichladdich lies in pushing these boundaries, experimenting with heirloom barley varietals and local Islay-grown rye. It is incredibly gratifying to witness how each grain translates into a spirit of distinct individuality.”