Sorry for the double post from the same blog today. This post is really important. It goes into the chemicals that Saccharomyces yeast produces. These chemicals make the flavors and aromas in our spirits. Read it. It will help you understand the complexity of what happens with yeast during fermentation.
The fermentation of wort into beer is a chemical transformation catalyzed by a group of microorganisms, both yeast and bacteria, that primarily produce carbon dioxide (CO2) and ethanol (CH3CH2OH). This is what I refer to as the “30,000 foot view” of fermentation. The Grand Canyon is beautiful looking out of the portal in the side of the airplane as you fly over, but to understand the Grand Canyon, you have to get your boots on the ground. It is common knowledge to even the most basic brewer or appreciator of good beer that there are other compounds that can be created as well, such as lactic acid (CH3CHOHCOOH) and other organic acids. But even with this added subtly, there are still dozens of additional compounds that lead to yeasts having unique flavors. Think about the difference between a hefeweizen yeast and an American ale yeast. The American ale yeast is far more “neutral” than the hefeweizen yeast, which might give you a banana or clove flavor. Both are Saccharomyces cerevisiae, but why do they taste so different? The answer is, the hefeweizen yeast produce more secondary metabolites that give it those flavors.