Beginner Home Distiller Series: Understanding Fermentation

Welcome to the exciting world of home distillation! In our first instalment of the Beginner Home Distiller series, we'll delve into the fundamental process of fermentation. Understanding fermentation is key to producing the perfect wash for your future spirits.

 What is Fermentation?

Fermentation is a natural biological process where yeast, a single-cell organism, converts sugar into alcohol and carbon dioxide. This magical transformation is the foundation of distillation, the art of crafting your own spirits.

What is Yeast?

Yeast is a microorganism that naturally occurs in the environment. They are extremely small and cannot be seen by the naked eye. But don’t let their size fool you – these tiny organisms are powerhouses that transform sugar-containing liquids into alcohol in a matter of days!

The Role of Oxygen and the Crabtree Effect

S. cerevisiae (the most common yeast species used for brewing) is a facultative anaerobe yeast which means they are able to grow and reproduce in a wide range of oxygen concentrations. Controlling yeast's access to oxygen is crucial for a successful fermentation process and even though they can grow anaerobically (in the complete absence of oxygen) they still require some level of oxygen. Adequate aeration during the initial stages of fermentation is crucial for maintaining yeast health and ensuring that an optimal yeast colony size is achieved to ensure a timely and successful fermentation.   

Does oxygen influence my alcohol concentration in the initial stages of fermentation?

No. Saccharomyces cerevisiae is subjected to the Crabtree effect. This allows the yeast to ferment instead of respiring, even under fully aerobic conditions in the presence of high sugar concentrations. This means that the yeast will still produce alcohol even in the presence of oxygen.

Is too much oxygen a problem?

Yes, because of two factors. The first is that too much oxygen can cause the oxidation of valuable aroma compounds which results in a loss of aroma quality in your final product. Remember, all the primary aroma compounds present in your final product is made during fermentation. The second being that when glucose becomes scarce, ethanol produced during fermentation is used as a carbon source, requiring a shift to respiration.

Why Use an Airlock?

An airlock is a vital tool in the home distiller's arsenal. It allows you to seal the vessel but at the same time allow carbon dioxide to escape, preventing pressure build up in the container. Sealing your fermentation container is not necessarily to keep out oxygen, but instead to protect your fermentation from unwanted contaminants. The fermentation process begins with a sweet mix rich in nutrients, providing an ideal environment for various organisms to thrive. By introducing yeast and sealing the mix with an airlock, we restrict access to unwanted microorganisms such as bacteria, fungi, as well as larger organisms such as insects and other pests.

Even with meticulous equipment cleaning, some unwanted elements may find their way into the wash. Yeast multiplies quickly, altering the environment by reducing pH (increasing acidity) and removing oxygen, creating an inhospitable environment for bacteria.

For a successful fermentation, maintaining sanitation, sealing the mix with an airlock, and adding yeast promptly are essential steps.

What is Sediment, and Why Does it Form?

As yeast performs its magical conversion of sugar into alcohol and carbon dioxide, it also reproduces, forming thousands of new cells. After fermentation, when there is no more sugar to consume, the yeast cells become dormant and drop to the bottom of the fermenter. Turbo yeast, in particular, can lead to significant sediment formation during this process.

Concluding remarks

Understanding these basics of fermentation sets the stage for your home distillation journey. Stay tuned for the next instalment as we explore the crucial steps in creating the perfect wash for distillation. If you would like to know more about the intricacies of yeast an fermentation be sure to enroll in our Y1 - ONLINE - Yeast and Fermentation Foundation Course.

Cheers to your distilling adventure!