When Dr. Don Livermore talks to distillery visitors about whisky, he always rolls out his flavour wheel (he prefers the Canadian spelling).

As master blender for Canada’s Hiram Walker & Sons, it’s a task he performs quite a bit, and his wheel, modeled after those used to teach about wine, significantly puts yeast at its heart as a coequal creator (with wood and grain) of flavors and aromas. He says people are always surprised.

“It’s a struggle for a whisky producer to talk about yeast.” —Dr. Don Livermore, Hiram Walker & Sons

“It’s a struggle for a whisky producer to talk about yeast,” says Livermore. “In our world, most people don’t even know yeast makes alcohol, and yet it provides so many flavors to whiskys. People don’t have that appreciation.”

“A lot of people would be surprised that, even with the time in a barrel and such, yeast makes a lot of difference,” says Chris White, CEO and founder of White Labs in San Diego, Calif. “The people who don’t think it matters haven’t tried it.”


Just a Commodity

By the late 20th century, yeast had mostly become a commodity in the world whiskey business, with efficiency and speed of fermentation the key markers. While whiskey distillers had long kept yeast “tubs” and labs in their facilities, the job has more recently been farmed out to suppliers. It’s quite a change from long ago, when distillers used special “brewing sticks,” covered with wild yeast, to stir and inoculate their mash.

In Scotland, most distillers since the 1950s have been using M strains of saccharomyces cerevisiae, the predominant yeast in spontaneous wine fermentation. “It always saddened me that [yeast] was the most horribly neglected part of the Scotch whisky production process. It was just viewed as a commodity,” says Dr. Bill Lumsden, director of distilling, whisky creation and whisky stocks at Glenmorangie.

“While we like to characterize yeast as being for beer or whiskey or wine, the yeasts don’t care what they’re fermenting.” —Kevin Lane, Fermentis

But the recent craft distiller boom shares roots with the craft brewing world, which has brought greater attention to yeast, says Kevin Lane, technical sales support manager – The Americas, for yeast producer Fermentis by Lesaffre, based in Milwaukee, Wis.

“I’ve been working for Fermentis for more than six years now and, from the beginning, I saw that distillers were starting to investigate different yeast strains for different whiskeys to produce more complex or different kinds of flavor in their whiskies.”


Creating Flavors

Different mash bills and malts, ancient grains, barrel finishing—all these techniques have been widely explored in chasing whiskey flavor in the past 20 years. So it was only a matter of time before distillers started looking to the microorganisms that ferment their recipes to create different flavors.

It’s never been a lost art at Four Roses Distillery in Lawrenceburg, Ky. Former parent company Seagram kept a library of more than 300 yeast strains for years, cataloging them by flavor profile. Four Roses developed a two-mash bill, five yeast strain process to make 10 distillates, made and aged in different combinations.

“They did that to have control over consistency of the final flavor and aroma of the whiskey,” says Brent Elliott, Four Roses’ master distiller and director of quality. That may have been the original purpose for using many yeasts, but now Elliott mixes and matches with different combinations of recipes to create products, such as Four Roses Small Batch, which includes four of the distillate recipes, Small Batch Select with six, and Single Barrel with one single recipe.

Four Roses Master Distiller Brent Elliot

Two of the yeasts, called Q and F, which have distinctive floral and herbal qualities, he uses sparingly as top notes. Now that the distillery’s single barrel retailer program has taken off (in which retailers visit and select their own favorite), many have chosen the herbal F or floral Q.

“When we started, I was sure the Qs wouldn’t go over well. They’re one-dimensional at five or six years, with great floral and candied fruit aromas but not a lot of complexity,” says Elliott. “But once they age out at nine to 11 years, those more powerful aromas reduce and the barrel notes emerge. There’s a crossroads where they really come together nicely.”

Now, he says, consumers trade 50 mL bottles of different single barrels on the whiskey underground (yes, there is such a thing). “Those folks really understand the importance of yeast strains now.”


Brewers Yeast Trials

Lumsden, whose doctorate is in fermentation science, says conversations with the late whiskey and beer writer Michael Jackson spurred him on 15 years ago to tinker with yeast. The result, released last year in the Private Edition series, is Glenmorangie Allta, created with yeast growing naturally on barley near the distillery.

Because one of the most abundant places to find yeast is in damp grain fields, his team gathered, incubated, and isolated more than one dozen yeast strains. Working with Montreal-based yeast firm Lallemand Biofuels & Distilled Spirits, they found one, Saccharomyces diaemath, to be ideal. The new make spirit, more earthy and spicy and less floral and fruity than classic Glenmorangie, reminds him of rising pizza dough.

“We were inspired by the way the brewing industry looks at yeast.” —Matt Hofmann, Westland Distillery

Other distillers are finding that brewers yeast yields interesting qualities. Matt Hofman, master distiller and co-founder of malt whiskey maker Westland Distillery in Seattle, Wash., has been using a Belgian saison brewers yeast from the beginning. “We were inspired by the way the brewing industry looks at yeast, and we were looking for something that went well with the flavors we were getting from our malts.”

For his mix of five malts, which Hofmann likens to a porter, he wanted a yeast that could impart a fruitiness for balance and brightness; the saison yeast gave him a mix of orange marmalade, pomegranate and raspberries, as well as pepper, cinnamon, and ginger.


Science and Spirits

Yeast advances have entered an interesting area recently, as Lallemand released Sourvisiae, a bioengineered ale yeast designed to produce lactic acid during primary fermentation, allowing brewers to make sour beers faster and more consistently. It’s one of the first times that genetically engineered yeasts are being marketed to beverage producers.

While there are dozens of yeasts targeting every style of beer, the major hurdles for a distiller using a brewing strain are the speed of fermentation and the strain’s ability to produce an appropriate flavor at a higher temperature, says Lane. “Beer strains aren’t suited to high temperatures of fermentation, some can [withstand it], but the flavor expected from a certain strain in a brewing application won’t be the same if you ferment hot and fast.” Whiskey distillers look at roughly a 72-hour fermentation, whereas brewers are typically used to a week to two weeks of fermentation.

“In brewing, the flavor and aroma produced by the yeast can be enjoyed relatively quickly, but with distilled spirits you must make sure those sensory characteristics remain after distillation.” —Sylvie Van Zandycke, lallemand

“The difference is that, in brewing, the flavor and aroma produced by the yeast can be enjoyed relatively quickly, but with distilled spirits you must make sure those sensory characteristics remain after distillation,” says Sylvie Van Zandycke, Ph.D director of sales and marketing brewing yeasts, bacteria and nutrients at Lallemand Brewing. “We do a lot of work to determine the congeners that remain after distillation. Obviously, you’re going to lose a lot of characteristics, but what stays is what matters.

“There’s a thirst for yeasts that can produce something that’s going to differentiate you from another small brewery or distillery. Yeast was never the raw ingredient that would come first to mind when it comes to flavoring, but now more and more it is.” To serve that market, Lallemand not long ago created a craft spirit division, where it offers yeasts to produce a variety of whiskey styles.

White Labs sells yeast to Heretic Distillery in Northern California (part of Heretic Brewing), who uses White’s best selling California ale yeast for his whiskies and even vodka. Chris White explains: “Since brewers yeast is selected for flavor purposes, [the customer, Jamil Zainasheff] thought, ‘Why not use it for my spirits?”

More are coming. “Some Scotch whisky distillers use unique yeast strains, but most have switched to the same set of industrial strains,” says White. “They used to combine brewers yeast and distillers yeast, but that’s been phased out for efficiency increases. That was at the cost of flavor contribution from brewers yeast. Distillers are now experimenting with a large variety of unique White Labs Brewing Yeast strains, and I’m excited to see the impact on Scotch and other spirits.”

Fermentis, too, has released a whiskey yeast strain that doesn’t have a geographic designation (like Scotch or American) but produces a more fruity character spirit. And Lane thinks it’s only the beginning.

“While we like to characterize yeast as being for beer or whiskey or wine, the yeasts don’t care what they’re fermenting, they just want to grow and survive,” he says. With some tinkering, some may turn out to offer terrific whiskies after all.

“There’s nothing wrong with the large-scale produced whiskies,” Lane continues. “They’re great whiskies and references in the market. But exploring different avenues to find different flavors or unique combinations is as exciting for the producer as it is for the consumer.”