Fermentation and Whisky | About Dram Time

In our ongoing series on whisky production, we’re turning our attention to fermentation. While malted barley and water are crucial, yeast holds the key to unlocking flavours in the new make spirit. Join us as we explore how different yeast strains and fermentation conditions shape whisky’s character.

While all three raw materials—malted barley, water, and yeast—play crucial roles in malt whisky production, yeast can have a significant impact on the quality and character of the new make spirit.

Yeast is responsible for converting fermentable sugars into alcohol and various flavour compounds during fermentation. Different strains of yeast can produce different flavour profiles, ranging from fruity and estery to more neutral or savory. Additionally, the fermentation conditions, such as temperature and duration, can also influence the flavour profile produced by the yeast.

By carefully selecting yeast strains and controlling fermentation parameters, distillers can tailor the character of the new make spirit to their desired specifications. This can include enhancing certain flavour notes, creating complexity, or maintaining consistency in the final product.

The duration of fermentation has a significant impact on the flavour profile of the new make spirit in whisky production. The interaction of yeast with barley sugars during fermentation produces a wide range of flavour compounds, and the length of fermentation can influence which of these compounds are dominant.

Shorter fermentation times, typically around 48 to 52 hours, tend to result in a spirit with more cereal and nutty characteristics. This shorter fermentation allows less time for yeast to produce fruity esters, emphasising the grainy notes instead.

Conversely, longer fermentation periods, ranging from 60 to 72 hours or even longer (up to 100 hours or more), can lead to the development of more fruity and floral aromas. Extended fermentation gives yeast more time to produce a broader range of flavour compounds, including fruity esters like those found in fresh fruits such as pineapple, peach, and apricot.

Distillers carefully manage fermentation times and conditions to achieve the desired flavour profile for their whisky, adjusting variables such as temperature, yeast strain, and fermentation vessel size to control the fermentation process and optimise flavour development.

Want to learn more about Whisky? Check out our ultimate whisky guide – download it here and expand your whisky knowledge.

Catch up on the rest of the series with our articles on Aqua Vitae, Water and Whisky and Barley Varietals.