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Art of whisky starts with science of chemistry

This is part of an ongoing series of stories exploring rye, the crop, as it becomes Rye, the whisky. Many tipplers talk about whisky-making as a craft…



This is part of an ongoing series of stories exploring rye, the crop, as it becomes Rye, the whisky.

Many tipplers talk about whisky-making as a craft or an art.

But long before whisky can become a work of art, the chemistry’s got to be done right. Whisky’s flavours come from the interplay of a number of chemical components that particularly favour the inclusion of rye in the grain base. That’s because rye is not like any other cereal grain.

Other stories in this series:

“Rye by far has the highest lignin and lignan levels,” said Don Livermore, the master blender for Canadian whisky giant Hiram Walker of Windsor, Ont.

“That’s why we use rye.”

For many Canadians, ordering a “rye” just means ordering a domestic whisky. For much of Canada’s whisky production, the amount of rye-derived alcohol included in the blend can be quite small because the average Canadian prefers a “light-tasting” whisky to a heavier, “spicy” one, according to Livermore. Canadian whiskies don’t have a mandatory amount of rye grain they have to include.

However, for those who fancy a more robust flavour, Canada’s distillers embrace the flavour punch that comes from fermenting and distilling rye grain. Certain rye components provide the spice associated with “rye” whisky, but that’s not necessarily based on a gross amount of rye in the grain blends that are used to create the finished product.

“Don’t ask me how much rye is in the whisky,” said Livermore, who has a Ph.D. in brewing and distilling.

“You’ve got to ask me how much of the (specific chemical compounds concentrated in rye grain) is in the whisky because that’s really what you’re asking me.”

Livermore’s education allows him to understand the chemical breakdown of the substances that come through the top of the whisky still, which is where rye grain’s value as a feed stock is obvious.

“This lignin just gets busted apart because of all the processing, the cooling, heating, distilling. It busts off the little snippets and chunks of it.”

Whisky flavours come from three basic sources: grains, yeasts and barrels. Unlike with liquor that is valued for its relative lack of flavour, such as vodka, whisky highlights the flavours of its components.

Rye grain adds a lot by itself because of its hardy kernel and physical structure, something that makes it hard to bake and ferment but provides it with strength in the field. Its environmental armour provides the sensory punch.

“I want to look at the shell, the outer layer that’s very fibrous,” Livermore said about the grain.

Unlike U.S. bourbon whisky, which must be produced through a “mash bill” of mixed grains that are fermented and distilled together, most Canadian distillers ferment and distil each grain component separately.

“If you separate things, you can control flavour at the blending.”

Tipplers might imagine alcohol distilled from a particular grain as being one essential substance, but in fact the alcohol that boils off through the column still — which can be a 65-foot tall, four-and-a-half foot diameter vertical tube — is a whole bunch of chemical components, some of which are unwanted and even dangerous.

Methanol, for instance, can cause blindness. There are also “green grass flavours that nobody wants” near the lower boiling points of the distillation spectrum. These are removed. At the other end of the scale, there are the “soapy” flavours from certain yeasts that please few palates and are also removed.

That leaves an array of substances that provide flavours of “butter, cherry, bananas, pear, strawberry, apples, apricot” at various distillation points, said Livermore. Near the top of the spectrum are the essential rye flavours, which can be separated.

“She knows the importance of rye and she knows where it comes out,” said Livermore of his master distiller.

“That is why distillers go to school.”

For Hiram Walker, it’s important for the rye-rich alcohols to be distilled only once because multiple distillations could strip it of its flavour. That’s why Livermore said the method of whisky-making can be more important than the specific percentage of rye in the blend.

Rye can be a tough grain to deal with, especially since it isn’t available in the vast standardized quantities common with big crops such as corn, wheat and barley. For many years, Hiram Walker relied upon rye crops grown on the sandy shores of Lake Erie by farmers needing a cover crop. That produced variable supplies because most of the farmers were using saved seed year after year and the grain was produced as a secondary consideration to the ground-covering function.

Since 2015, the company has moved to requesting specific varieties from farmers, such as Brasetto. These varieties come from Europe, especially from seed giant KWS, and are mostly hybrids.

Livermore said the increased uniformity of the hybrids is a blessing for distillers and he expects to see the move into specific varieties become permanent.

Agronomic practices are also coming into focus, Livermore said. Distillers must watch out for a carcinogenic substance, ethyl carbamate, appearing in the alcohol, and that can be created by some of rye grain’s chemistry. When ethanol interacts with urea in the distillation, ethyl carbamate can develop, something that only appears during distillation.

Can rye growers manage their crop so that fewer precursors to ethyl carbamate develop in the grain?

“It’s one of the things we’re going to look at in the next 10 years,” said Livermore.

Also, grain storage can create some stinky surprises. Most whisky tipplers don’t want a “musty, fish-tanky” smell in their glass, but that’s what can appear in the distilled alcohol if geosmin develops from fungus in the grain bin.

Managing rye grain in storage is also likely to become a bigger concern in coming years as the grain draws a greater focus in the whisky-making process.

Livermore revels in the freedom that blending “Canadian” whisky affords him and the multiple brands he oversees. Some people like a very light whisky, and many versions of that can be made through blending. Spicier “rye” whiskies can also be blended for a spectrum of palates.

However, he clearly values being able to produce the flavour-rich “Canadian” and “rye” whiskies for which this country is famous. These flavourful tipples are appreciated around the world.

Funnily enough, rye whisky is less recognized and lauded in Canada than the United States. There is some confusion in Canada over what “rye” whisky means, but down south rye whisky has experienced a renaissance in production and popularity as one of America’s earliest whisky types regains some of its former share in both quantity and regard.

Hiram Walker proudly boasts of the rye-ness of many of its premium whiskies. So too do other Canadian distillers, such as Alberta Distillers.

Rye is making a comeback against Scotch whisky, which holds the throne in the whisky kingdom. It’s hard to imagine a day in which Rye will be as highly regarded as Scotch among uisgephiles.

Funnily enough, Rye and Scotch share a common component: lignin.

The peat that dries and smokes barley for Scotch is just a form of “broken down” lignin from centuries of moss growth. Some Scotch lines extract much flavour from the peat, as Rye whisky does from the rye grain’s husky nature.

“One way or the other, lignin really does drive the flavour of whisky,” said Livermore.

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