Fermentation is an essential step for the making of beer.It is defined as the process where the yeast transforms the sugars from the barley must into ethanol and carbon dioxide. The different genera or species of yeasts will result in very different beers which will be explained in another blog. Depending on the type of yeast used in fermentation, beers are divided into two large groups: lager or low-fermentation beers (which do so at temperatures between 5-10⁰C and ale or high-fermentation beers (between 17 and 25⁰C)To control the beer fermentation process a little better, we can differentiate three stages:1. As soon as the yeast is added to the fermenter, the first stage known as Lag will begin. It is important that this stage is as short as possible and that it does not exceed 24 hours. At the end of this stage, a foam (Krausen) will form at the top and is usually cream in color. This foam protects the must from possible contamination.
2. In the second phase the yeast begins to ferment the must and begins to release CO2. In the Airlock (bubblers) you can observe the activity inside the fermenter when CO2 is released. This stage lasts a few days during which the Krausen decreases.
In the last stage, also known as conditioning, the yeast removes by-products that make the beer worse, such as esters and diacetyl.
