Whisky begins with grain. After milling, fermenting and distilling, the resulting spirit is left to sit in oak barrels. Within this taste-changing wooden cocoon, it becomes a rich, highly variable liquid with flavours that make it one of the world's most desired and discussed drinks - whisky. That flavour though, where does it come from? There are five primary flavour sources in whisky: grain, yeast, wood, age and diffusion. What begins with grain and is influenced by wood is shaped by the passage of time.
Grain and wood share many characteristics. Like wood, grain is composed of long carbohydrates called cellulose and hemi-cellulose, which are held together by a third molecule called lignin. "Grain or wood," says Livermore, "cellulose and hemi-cellulose are the bricks, and lignin is the mortar." However, there's a lot more to whisky flavour than the grain it begins with and the wood in which it matures. In this, the first of a two-part series, we look at flavour development up until the spirit leaves the still. In the next piece we will examine what happens in the barrels.
Canadian whisky is ideal for studying flavour development because each component of the whisky is processed individually. Additionally, Canadian whisky is made by blending two different kinds of spirit. One is called 'base spirit' and is distilled to a high ABV. This removes many of the flavours generated during fermentation, leaving a lighter spirit that is perfect for studying what happens during maturation. The second type of spirit is called 'flavouring' and is distilled to a low ABV to concentrate the flavours of fermentation. This spirit is well suited to studying flavours that develop before maturation. If you ask Dr Livermore how much rye is in one of his whiskies he'll politely say you are asking the wrong question. "Don't ask how much rye, ask how it was distilled," he insists. Just as the still can concentrate flavour, it can also strip it out. For example, there are several 100 per cent rye whiskies on the market that exhibit virtually no 'rye' character whatsoever.
What about those flavours that the still concentrates? "Outside of starch, it's cellulose, hemi-cellulose, and lignin that drive the flavours that come from grain," he says. "During milling, cooking and distillation, lignin that holds the grain together is broken down into its building blocks which are the flavours we taste in whisky. Lignin is the primary source of grain flavours that survive the brewing and distillation processes." However, in addition to the grain there's a silent partner, rarely mentioned, but equally influential: yeast.
"Most importantly," says Livermore, "grain contains the carbohydrate, starch." Using heat and enzymes, distillers convert this starch into sugar. Yeast is a sugar-eating, alcohol-excreting living creature. It also excretes flavourful esters and other flavour-building chemicals, such as fatty acids. With precise laboratory equipment, Livermore has measured the concentration of various flavour chemicals, called congeners, in new and maturing spirit. His research confirms that the highest concentration of congeners comes from yeast and not from grain. Thus, creative whisky makers can influence flavour because yeast cells, like most living things, respond to how they are treated. Raise the temperature of the fermenting mash and they make more fruity, floral esters and fewer fatty acids. Reduced oxygen levels in the mash lead to more esters and fatty acids. Even stirring the mash changes the resulting mix of congeners. "We are brewers as well as distillers," is how he summarizes it. As simple as this sounds, there is another factor that significantly complicates matters. "Even though numerically the yeast flavours are higher," he continues, "there is also a potency factor associated with each flavour component." One particular component might have a greater impact at concentrations of parts per billion, than another that is present in parts per million.
Livermore has used gas chromatograph mass spectrometry (GCMS) to sort the various congeners derived from fermentation into two groups: those that originate in the grain and those created by the yeast. With this information he has been able to identify the source of flavour in his component whiskies and create final blends that showcase each source. Let's begin with two whiskies from which we learn to differentiate grain flavours from yeast flavours.
The flavours of grain
Gooderham & Worts is a time-honoured name in Canadian whisky. Livermore inherited the original Gooderham and Worts recipe books, but for this blend he began afresh. His new Gooderham & Worts whisky is a four-grain blend that is all about the flavours of the grain.
To highlight these, he blended corn base whisky with wheat, barley, and rye flavouring whiskies. Some bready, caramel notes, he observes, come from furfural that was created by browning (Maillard reactions) in the still. However, the obvious cereal flavours began as lignin in the grain's outer covering - the bran. "You taste the heady wheat notes first," says Livermore. "Then the nutty barley. Corn sweetness comes through next and finally the rye spices - that warm feeling in your chest." It's like drinking liquid grain.
The flavours of yeast
He pours me a dram of Lot No. 40, a 100 per cent rye/grain flavouring whisky. His GCMS (and his nose,) indicate that yeast flavours dominate. "Be careful on this," he warns. "Remember there is also a potency factor with each flavour whether it comes from yeast or grain or wood." The primary flavours of Lot No. 40 are from yeast and not grain, he assures me. Where I smell lilacs he finds roses; we both taste dark fruits. These are all yeast-generated esters. There assuredly is some rye spiciness which he says originates in the rye grain, and also in the wood. "Wood and rye grain share flavour components, though they differ in proportions and thus have very different flavour expressions."
"Yeast contributes 25 times more flavour components than wood or rye; however the flavours that come from rye and wood are very potent in comparison to yeast flavours and one could argue influence the final product even more." Lot No. 40 is a massive whisky, combining spring flowers, exotic fruits, baking spices, vanilla, and scorching pepper before finishing on sour rye and gentle tannins.
Few people find newly distilled spirit to be very palatable. Nevertheless, even before that new make is filled into barrels, some whisky flavours are already present. Where those flavours arise though, is not as obvious as it seems. The fruity floral notes that we so often equate with rye actually come from yeast. Distillation practices too, make a huge difference in which flavours will be expressed in the final product.
Next time we will look at flavour development in the barrel, where wood, time and diffusion transform a rough, raw and often uninviting spirit into the golden elixir we call whisky.
Gooderham & Worts 44.4% ABV
Developed to enhance the flavours of grain, there are hints of green notes, big cereal, soft creamy wheat and buttery corn with suggestions of dusty rye, baking spices and nutty barley accented with white pepper, citrus pith and velvet oak tannins. Whisky of the Year material with the grain front and centre.
Lot No 40 43% ABV
This quintessential rye whisky showcases the flavours of yeast with spring blossoms - apple, cherry, lilac and dark plummy fruits with tropical fruit nuances. Bavarian rye bread, wet slate and a range of rye spices show that although yeast flavours dominate, some rye grain has crept in there too. A truly best-crafted whisky.