How to Whisky: Why Yeast is the Invisible Brain Behind Your Whisky

Sunday, 07 September 2025 at 15:02

You can't see it, but you can taste it without knowing: yeast. What is the role of yeast in the making of whisky and why is it sometimes called the silent strength? In this How to Whisky, we put yeast in the spotlight.

FAQ

What exactly is yeast?
A microscopic single-celled microorganism (a fungus) that can be found everywhere.

What does yeast do in whisky production?
It turns sugars from grains into alcohol and provides the flavors and aromas.

Where do distilleries get their yeast from?
From commercial suppliers, their own heritage-strains, wild catch, or a clever mix of multiple strains.

What exactly is yeast?

If you've ever visited a distillery or brewery, you've undoubtedly heard stories about yeast and yeast strains. This tiny, yet powerful organism, is extremely important for the production of the divine drink.

In essence, yeast is nothing more than a single-celled fungus. With this single cell, yeast ensures that sugars are converted into alcohol and carbon dioxide. It is essential for example for bakers who want their bread to rise and is used in the making of beer and whisky.

There are more than 1500 types of yeast, but when making whisky, for example, Saccharomyces cerevisiae is very important. You do not need to remember this name, you can also refer to it as brewer's yeast.

There are countless strains of this type of yeast. Depending on the strain, yeast can conjure up fruity, spicy or floral notes in your whisky. So it's as if there is an invisible worker in the distillery, casting spells with flavors and aromas.

The large Mash tun at Glen Scotia Distillery in Campbeltown

How does yeast make alcohol for whisky?

During the whisky-making process, yeast only comes in after the mashing. Yeast is added to the cooled mash: a tablespoon for every five gallons of mash.

Then begins the fermentation that lasts numerous hours. The yeast first multiplies at lightning speed and then gets to work with the sugars.

In the case of Blair Athol, the fermentation is relatively short, namely between 46 and 50 hours. With other distilleries like Glen Scotia, this can last up to a week or even longer. During this process, esters are also created: chemical compounds that deliver fruity and sometimes floral aromas.

Once the sugars are depleted or the alcohol becomes too strong, the yeast dies. And just in that final life phase, the fungus drops a flavor bomb that distillers highly appreciate.

Whisky experiments with yeast

Some distilleries consistently choose a single type of yeast. After all, it's a familiar and trusted recipe that ensures a particular taste. Other distilleries are more daring and conduct experiments with yeast. They use old types of yeast, mix yeast types (co-fermenting), and thus discover new effects during fermentation and new flavors for their whisky.

Though an invisible force in your glass, yeast is of invaluable worth. Next time you hold a glass of whisky, also cheers to the billions of cells that have made everything in your glass possible.