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The primary role of yeast is to convert the sugars present (namely glucose) in the grape must into alcohol.The yeast accomplishes this by utilizing glucose through a series of metabolic pathways that, in the presence of oxygen, produces not only large amounts of energy for the cell but also many different intermediates that the cell needs to function.
Bottle fermentation is a method of sparkling wine production, originating in the Champagne region where after the cuvee has gone through a primary yeast fermentation the wine is then bottled and goes through a secondary fermentation where sugar and additional yeast known as liqueur de tirage is added to the wine. This secondary fermentation is ...
This phenomenon is known as the Pasteur effect. However, many yeasts such as the commonly used baker's yeast Saccharomyces cerevisiae or fission yeast Schizosaccharomyces pombe under certain conditions, ferment rather than respire even in the presence of oxygen. In wine making this is known as the counter-Pasteur effect.
Their end products are also highlighted. Figure modified from Hackmann (2024). [1] Fermentation is a type of redox metabolism carried out in the absence of oxygen. [1] [2] During fermentation, organic molecules (e.g., glucose) are catabolized and donate electrons to other organic molecules. In the process, ATP and organic end products (e.g ...
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.
This is likely due to lactose intolerance, a condition making it hard to digest lactose, a sugar found in dairy products. Most newborns are able to produce lactase, an enzyme crucial for the ...
Autolysis in winemaking relates to the complex chemical reactions that take place when a wine spends time in contact with the lees, or dead yeast cells, after fermentation. While for some wines - and all beers [ 1 ] - autolysis is undesirable, it is a vital component in shaping the flavors and mouth feel associated with premium Champagne ...
Esters: [2] Ethyl acetate is the most common ester in wine, being the product of the most common volatile organic acid — acetic acid, and the ethyl alcohol generated during the fermentation. Norisoprenoids , such as C13-norisoprenoids found in grape ( Vitis vinifera ) [ 8 ] or wine , [ 9 ] can be produced by fungal peroxidases [ 10 ] or ...