🍷 Alcoholic fermentation

Alcoholic fermentation is the process in which yeast eats the sugar of the must and releases alcohol and carbon dioxide. This is how grape juice becomes wine.

Must contains sugar. Yeast, most often Saccharomyces cerevisiae, converts it into ethanol, that is alcohol, and carbon dioxide. The gas escapes and the alcohol stays in the wine. Heat is released, so the fermentation temperature is monitored: whites usually ferment cooler, reds warmer. Red must ferments together with the skins, and a cap of grape solids forms on top, which is periodically pushed down into the liquid.

Fermentation lasts from a few days to a couple of weeks, sometimes longer. It ends when the sugar is eaten up, or it is stopped by hand to leave some sweetness. That is called stopping fermentation. Alcoholic fermentation is part of the general idea of fermentation but differs from malolactic fermentation, which is carried out by bacteria. A similar process takes place in kumis, but there is very little alcohol in it. For people it is one of the oldest technologies, on which wine production rests.