Alkoholikäyminen

Alkoholikäyminen, also known as alcoholic fermentation or ethanol fermentation, is a biochemical process that converts sugars into ethanol and carbon dioxide. This process is carried out by certain microorganisms, primarily yeasts and some bacteria, in the absence of oxygen. It is a type of anaerobic respiration.

The primary sugar used in alcoholic fermentation is glucose, but other sugars like fructose and sucrose can also be fermented. Yeast, specifically species like Saccharomyces cerevisiae, are the most common agents. During fermentation, enzymes within the yeast break down glucose into pyruvate. Pyruvate is then further processed into acetaldehyde, releasing carbon dioxide as a byproduct. Finally, the enzyme alcohol dehydrogenase converts acetaldehyde into ethanol.

This process is fundamental to the production of many alcoholic beverages, including beer, wine, and spirits. In brewing, it occurs after the wort, a sugary liquid derived from malted barley, is prepared. In winemaking, it is the conversion of sugars present in grape juice. Distillation can then be used to increase the alcohol concentration of these beverages.

Beyond beverages, alcoholic fermentation is also utilized in baking, where the carbon dioxide produced causes dough to rise. In some industrial applications, it is used for the production of biofuels like bioethanol. The efficiency and outcome of alcoholic fermentation can be influenced by factors such as temperature, pH, and the presence of specific nutrients.