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Ethanol fermentation, also called alcoholic fermentation, is a biological process which converts sugars such as glucose, fructose, and sucrose into cellular energy, producing ethanol and carbon dioxide as by-products. Because yeasts perform this conversion in the absence of oxygen, alcoholic fermentation is considered an anaerobic process.
The natural occurrence of fermentation means it was probably first observed long ago by humans. [3] The earliest uses of the word "fermentation" in relation to winemaking was in reference to the apparent "boiling" within the must that came from the anaerobic reaction of the yeast to the sugars in the grape juice and the release of carbon dioxide.
In ethanol fermentation, one glucose molecule is converted into two ethanol molecules and two carbon dioxide (CO 2) molecules. [10] [11] It is used to make bread dough rise: the carbon dioxide forms bubbles, expanding the dough into a foam. [12] [13] The ethanol is the intoxicating agent in alcoholic beverages such as wine, beer and liquor. [14]
Grapes being trodden to extract the juice and made into wine in storage jars. Tomb of Nakht, 18th dynasty, Thebes, Ancient Egypt. Sourdough starter. In food processing, fermentation is the conversion of carbohydrates to alcohol or organic acids using microorganisms—yeasts or bacteria—without an oxidizing agent being used in the reaction.
In the making of white wine it can be added prior to fermentation and immediately after alcoholic fermentation is complete. If added after alcoholic fermentation it will have the effect of preventing or stopping malolactic fermentation, bacterial spoilage and help protect against the damaging effects of oxygen. Additions of up to 100 mg per ...
Pyruvate decarboxylase occurs as a dimer of dimers with two active sites shared between the monomers of each dimer. The enzyme contains a beta-alpha-beta structure, yielding parallel beta-sheets. It contains 563 residue subunits in each dimer; the enzyme has strong intermonomer attractions, but the dimers loosely interact to form a loose ...
A 16th-century brewery Brewing is the production of beer by steeping a starch source (commonly cereal grains, the most popular of which is barley) in water and fermenting the resulting sweet liquid with yeast. It may be done in a brewery by a commercial brewer, at home by a homebrewer, or communally. Brewing has taken place since around the 6th millennium BC, and archaeological evidence ...
This critical value, above which alcoholic fermentation occurs, is dependent on the strain and the culture conditions. [5] More recent evidences demonstrated that the occurrence of alcoholic fermentation might not be primarily due to a limited respiratory capacity, [6] but could be caused by a limit in the cellular Gibbs energy dissipation rate ...