Yeast is extremely important in the alcohol distillation process. Whether you are making vodka, rum, or whiskey it is extremely important that you use the proper yeast to minimize the production of undesirable fusel alcohols, aldehydes, and other byproducts and impart the proper flavor to the alcohol.
The fermentation process uses yeast to convert fermentable sugars into alcohol and carbon dioxide by breaking down sugar’s molecular structure of into simpler compounds. The type of yeast used greatly affects fermentation rate and overall flavor of the finished product – if you use the wrong yeast, you could ruin your batch.
Typical yeasts used in brewing and distillation are members of the genus Saccharomyces, and they have been cultivated to thrive in the fermentation industry. Yeast strains have dramatically differing nutritional requirements for strong and rapid fermentation, so proper yeast is absolutely essential.
Fermentation takes place in different phases – the first being primary fermentation. In the primary phase, yeast uses oxygen and other nutrients to rapidly grow and reproduce. After the initial growth, they kick into gear and start breaking sugars down in order to use the oxygen molecules.
Contrary to popular belief, yeast doesn’t just feed on sugar – it needs other nutrients like nitrogen and uses sugar for oxygen. After the sugar is broken down, the main byproducts created by the yeast are CO2 and alcohol. They aren’t trying to create alcohol; they are doing their best to survive in a hostile anaerobic environment.
Fun fact: Yeast is fastest organism on the planet that can mutate and adapt to survive in a hostile and changing environment.
As the nutrients start to run out, the fermentation process slows down and the yeast converts sugars to alcohol at a much slower rate. The CO2 bubbling will start to settle down and the dead yeast will settle at the bottom of the fermentation tank.
The wash that is left is a mixture of alcohols, unfermented sugars, and other molecular compounds that are let behind after the fermentation. Now, it is time to move on to the distillation phase.