A Few Thoughts On Yeast and Fermentation

Back in 2015 I wrote a blog about yeast and it covers a lot about the subject, but I thought I would write a few more thoughts on the subject here.

Yeast has always been an important part of American whiskey. Back in the 19th century, distillers would collect yeast strains and propagate the strain they thought made the best whiskey. Many of them called themselves “distiller and yeast maker” to emphasize the importance of their yeast strain management. All yeast strains are not created equal. Different strains of yeast produce different flavors in the whiskey. Four Roses is a master of this concept as they have five different strains of yeast and two different mash bills, making ten different whiskeys. Yeast was a closely guarded secret for the distillers in the 19th century and distillers protected their strains throughout the year, carefully propagating it year round. In the 20th century, particularly after World War Two, when there was a consolidation of the industry, yeast strains were more available to the surviving distilleries. For most of the time throughout the 19th and the first half of the 20th centuries, yeast was kept in a dona jug and propagated from a liquid slurry of malted grain and yeast. In the latter half of the 20th century, dry yeast became common as distillers wanted to save money on production and eliminating the costly yeast making process saved them money.

Today a distiller can purchase a yeast strain from companies like FermSolutions and pick the flavor profile they want in their whiskey. These companies keep a library of different yeast strains and can propagate the strain the distiller desires. Yeast is not a closely guarded secret like it was in the 19th century.

Yeast is just one part of the fermentation stage of distilling. There is also the length of fermentation. Most distilleries use a three day fermentation period to make their beer. It is cost effective and produces excellent whiskey. However, the longer you let the beer ferment, the more the flavor of the beer changes. Woodford Reserve Distillery lets their beer ferment for five days because they like the additional flavor produced by the yeast in the beer. Long weekends due to holidays can cause distillers that use three day fermentation to produce some beer with four day fermentation. There will be subtle changes in the flavor from these longer fermentations but most distillers will blend this whiskey with their normal whiskey and the consumer will not notice the difference.

These are a few of my thoughts on yeast and fermentation. I hope you enjoyed the random thoughts of my wandering mind.