Alkoholkäärimine

Alkoholkäärimine, also known as alcoholic fermentation, is a metabolic process that converts sugars into ethanol and carbon dioxide. This process is carried out by yeasts and some bacteria in the absence of oxygen. It is a key step in the production of alcoholic beverages such as beer, wine, and spirits, as well as in the leavening of bread.

The primary sugar fermented is glucose, although other sugars like fructose and sucrose can also be utilized. The overall reaction can be summarized as: C6H12O6 (glucose) -> 2 C2H5OH (ethanol) + 2 CO2 (carbon dioxide). This reaction is catalyzed by a series of enzymes within the yeast cells.

The process begins with glycolysis, where glucose is broken down into pyruvate. In anaerobic conditions, pyruvate is then converted to acetaldehyde, releasing carbon dioxide. Finally, acetaldehyde is reduced to ethanol by the enzyme alcohol dehydrogenase, regenerating NAD+ which is essential for glycolysis to continue.

Alkoholkäärimine is a complex biochemical pathway with many intermediate steps and regulatory mechanisms. The efficiency and outcome of the fermentation can be influenced by factors such as temperature, pH, the specific yeast strain used, and the availability of nutrients. In bread making, the carbon dioxide produced causes the dough to rise, while the ethanol evaporates during baking. In the production of alcoholic beverages, the ethanol produced is the desired product.