Kids, don't try this at home. Fermentation Fermentation is a process that involves microscopic fungii called yeast. These microorganisms convert certain sugars into alcohol and carbon dioxide in the absence of oxygen. There are several factors that are required for healthy fermentation. Sugar is the basic food that yeast needs to survive.
Yeast eats the sugar and converts it to alcohol and carbon dioxide.
There are several kinds of sugar that are usable by yeast. Larger molecules such as dextrins and starch are not usable by yeast. In order to get a good start, yeast requires oxygen for initial growth. If it doesn't have enough oxygen initially, it will take a long time for the brew to ferment. Yeast requires certain nutrients such as soluble nitrogen, B vitamins, and minerals.