When you think of whisky, images of golden drops, aged oak barrels and stills often come to mind. But a crucial factor in whiskey production that is often overlooked is yeast. This microscopic organism has a great influence on the taste, aroma and final quality of whisky.
What is Yeast?
Yeast is a type of fungal organism that plays a central role in many fermentation processes. In whiskey production, yeast is used to convert the sugars in the malted barley into alcohol and carbon dioxide. This happens in a process called fermentation.
The Role of Fermentation
In whiskey production, the ground barley is mixed with water to create a "mash." This mash is then heated to promote the enzyme activity that converts the starch into sugar. Yeast is then added and the fermentation process begins. Fermentation usually lasts between 48 and 96 hours, depending on the distillery and the style of whiskey desired.
Fermentation not only produces alcohol and carbon dioxide, but also a number of other substances, such as esters, phenols and higher alcohols. These contribute to the whiskey's complex flavor profile. The type and quantity of yeast, the temperature of fermentation and the time at which fermentation is stopped can all have a significant impact on the final taste of whisky.
Variations in Yeast
Some distilleries use "wild" yeast strains found naturally in their local environment, while others use commercial yeast strains to achieve more consistent results. Some experimental distilleries are also trying to revive historic yeast strains to recreate old whiskey styles.
Yeast is an under-recognized but critical ingredient in whiskey production. Without this microscopic helper, we wouldn't have the complex and beloved drink we know as whiskey. The next time you enjoy a glass, it might be worth considering how the yeast's invisible hand has shaped your experience.