For decades, yeast in whisky was a behind-the-scenes player, important but barely acknowledged. Traditionally, its role was seen as functional, converting sugars into alcohol, while the focus was on grain, oak, and time.
But over the past few years, yeast has stepped into the spotlight, with distillers beginning to recognize it as a key contributor to whisky’s flavor. From Scotland to America and England, yeast is now being viewed not just as a tool for fermentation but as a creative force in shaping whisky’s character.
Scotch: The Conservative Core of Yeast Fermentation
In Scotland, yeast has long been treated as a necessary but unremarkable ingredient. As whisky writer Dave Broom once quipped, when it comes to fermentation, the typical Scottish distillery script is: “Then we add yeast”.
With the focus on large-scale production, distilleries have traditionally relied on fast-acting industrial yeast strains that ferment quickly and efficiently. These yeasts are used to create a clean and neutral wash, allowing the cask to do most of the work in developing flavor.
Historically, Scottish distillers used ale yeast from nearby breweries, but the industrialization of scotch whisky production in the 20th century led to the adoption of pure cultured yeast. By the 1960s, nearly all major distillers had switched to lab-controlled strains. As a result, most scotch whisky today uses industrial yeast that prioritizes alcohol production over flavor creation.
However, change is beginning to occur in a small number of distilleries. Glenmorangie’s Allta, released in 2019, was fermented with a wild yeast isolated from barley fields near the distillery. The goal was to explore yeast’s potential to add flavor, with the result being a new make spirit with bready, floral notes. The Glenmorangie Company’s Dr. Bill Lumsden emphasized the untapped potential of yeast in flavor development, in an article by Becky Paskin: “Yeast’s influence on taste has been overlooked for years,” he said, “but it’s an area ripe for exploration.”
InchDairnie Distillery is also experimenting with multiple yeast strains for fermentation, focusing more on flavor than alcohol production.
During a visit to Port of Leith Distillery in Edinburgh in 2024, I learned that the distillery is committed to researching how yeast can influence the flavor of their new make. According to our tour guide, Adeline, 24 strains had been researched and 72 samples produced at that time. All of these strains will be experimented with as Port of Leith works towards releasing its first in-house single malt.
These examples, though still rare, signal a growing Scottish interest in how yeast can shape whisky. As more distilleries begin to explore yeast’s potential, the question becomes: if yeast can shape character as much as wood or barley, why not give it more of a spotlight?
American Whiskey: Falling Back in Love with Yeast
In the United States, yeast has always played an important role, but for much of the 20th century, it was largely kept in the background. Many Kentucky bourbon distilleries maintained their own proprietary yeast strains, often passed down through generations. In the Beam and Dant family, the iconic jug yeast has reportedly been used since Prohibition.
However, in recent years, American craft distillers have rediscovered yeast as a key ingredient in flavor creation. Wilderness Trail Distillery in Kentucky, founded by fermentation scientists, uses a sweet mash process that gives yeast more room to express itself. This method requires cleanliness and precision but allows the yeast to create a rich, ester-heavy spirit with tropical fruit and floral notes even before it touches a barrel.
At Four Roses, yeast has always been an integral part of the distillery’s identity. The company uses five proprietary yeast strains, each with its own flavor profile: floral, spicy, or fruity. By combining these yeast strains with two different mash bills, Four Roses creates ten distinct bourbon recipes. Yeast is so important to their process that it’s listed on their labels, allowing bourbon drinkers to seek out specific flavor profiles.
In these American distilleries, yeast is no longer just a behind-the-scenes component. It is now recognized as a critical part of the whiskey-making process, adding unique flavors and complexity to the spirit.
English Whisky: Experimental and Yeast-Driven
English whisky, still in its infancy, is rapidly becoming a hub for yeast innovation. Without the centuries-old traditions and regulations that govern Scottish production, English distillers are free to experiment and embrace yeast as a key part of their production process.
Additionally, there is a high proportion of brewing and distilling crossover amongst English whisky makers, with many distilleries being born of already established brewing operations.
At Grasmere Distillery in the Lake District, Paul Abbott, a brewer, is using ale yeasts and cold fermentations to create new make spirits with bright, fruity flavors. The distillery’s goal is not to rely solely on the cask to create flavor but to build complexity from the very beginning. The result is a whisky that showcases fruit and floral esters even before maturation.
Lancaster Spirits Co., just south of Grasmere, uses a 200-year-old brewer’s yeast that was originally isolated in the 1800s. This historic yeast, along with a slow fermentation process that can take up to seven days, creates a whisky with deep, aromatic complexity. Lancaster even bottles its new make spirit, confident that its flavor profile is bold enough to stand on its own.
Cotswolds Distillery, influenced by the late Dr. Jim Swan, uses two distinct yeast strains, one for yield and one for flavor, during fermentation. The result is a bright, fruity new make spirit that demonstrates how yeast can shape whisky even before it enters the cask.
Culture vs. Capacity: Why Yeast Innovation is Evolving
The way different whisky regions approach yeast is shaped by their respective production traditions and capacities. In Scotland, large-scale production is the norm, and consistency and efficiency are key to maintaining a large-scale customer base.
Most distilleries use fast-acting yeast strains that produce a clean wash with minimal influence on flavor. The focus remains on the maturation process and what the cask can impart to the whisky in terms of character.
In the United States, particularly among craft distillers, yeast is seen as an essential part of the flavor creation process. With smaller production scales and a focus on quality, these distillers have the freedom to experiment with different yeast strains, fermentation methods, and processes. For them, yeast is just as important as the grain and wood in defining the whisky’s identity.
In England, the relatively young whisky industry is not weighed down by tradition, giving distillers the flexibility to experiment. (At least, for now. The English whisky GI debate continues.) Extended fermentation times and different yeast strains are used to create distinct flavors from the very start, leading to innovative, yeast-driven whiskies that challenge traditional norms.
Why Yeast Matters More Than You Think
The idea that 80% of a whisky’s character comes from the cask is widely accepted, but many believe that this oversimplifies the process. While the barrel plays a significant role in developing complexity, it can only enhance the flavors already present in the spirit. Yeast and fermentation lay the foundation for these flavors, producing the fruity esters, spicy phenols, and floral aldehydes that define a whisky’s character.
Glenmorangie’s Allta and Four Roses’ yeast-driven bourbons show how yeast can shape a whisky’s flavor long before maturation. These distilleries have demonstrated that fermentation is not just functional but fundamental to creating complex, unique whiskies.
The Yeast Revolution
The whisky world is beginning to recognize what brewers and winemakers have known for centuries: yeast is not just a tool for fermentation but a creative partner in flavor creation. Distilleries like Glenmorangie, Wilderness Trail, Grasmere, and Lancaster Spirits Co. are leading the way in exploring yeast’s potential, and this shift is reshaping whisky’s future.
For whisky drinkers, this new focus on yeast means more variety, complexity, and exciting possibilities. The barrel will always have its place, but yeast is finally emerging from the shadows to become a driving force in whisky innovation.
Do you have any favorite whiskies that are produced using particular yeast-forward methods? Or do you think that yeast is overrated? Let us know in the comments below.
Read the full article at Scotch vs. American vs. English Whisky: The Yeast Divide
