Alcoholic fermentation
What is it?
Alcoholic fermentation is a bioligical procces, without oxygen, it is beginin by the activity of some microrganisms that process carbohydrates (sugars, for example glucose, fructose), to ultimately obtain alcohol in the form of ethanol, carbon dioxide, in the form of gas and adenosine triphosphate molecules consumed by microorganisms in energetic cellular metabolism. The resulting ethanol is used in the production of other alcoholic beverages, such as wine, beer, cider, ...
The formul of alcoholic fermentation
Yeast, fungus
To carry out this process is necessary the presence of yeasts, microscopic fungi that are found naturally in the skins.
Oxygen is the initial trigger of the fermentation, because the yeasts will need it in its growth phase. However, at the end of the fermentation, it is good that the presence of oxygen is small to avoid the loss of ethanol and the appearance of acetic acid or acetyl instead.
96% of the production of ethanol is carried out by microscopic fungi, yeasts, among which are found as Saccharomyces, Kluyveromyces, Torulaspora and Zymomonas
Image of Saccharomyces cerevisiae
Condition
Image of yeast Kluyveromyces fragilis
At a lower temperature, it is easier to get a higher alcohol content, since it seems that the high temperatures that make yeasts ferment faster
The most adequate temperature for alcoholic fermentation is between 18-23ºC and is the one most commonly used in the production of white wines. However, to make red wines one of the grapes is necessary in order to extract anthocyanins and tannins mainly, so that it is fermented at higher temperatures (24-31ºC) to seek a greater extraction of these compounds.
Above 33-35ºC, the risk of stopping fermentation is very high, as is the risk of bacterial alteration, since at these high temperatures the cell membranes of the yeasts cease to be so selective, emitting very suitable substrates for the bacteria