what is the role of fermentation in wine making?

Question

oh... its an experiment!

Answer 1

Fermentation is the process in which yeast eats the sugars in the grape juice and converts them into CO2 and alcohol.

Answer 2

Science of Wine

Wine is an alcoholic beverage made from fermented grape juice. Wines made from other fruits are always named accordingly. A glass of wine is a mixture of chemicals, and drinking it stimulates your body and mind. The chemical composition of wine is about 87.7% water, 11% alcohol, 1% acid, and 0.2% tannins.

There are many steps in making and producing the wine. Firstly, the grapes are allowed to ripen in the vineyard until they attain suitable sugar content, which is about 18% or more, and acidity. During ripening in the vineyard, grapes may become infected by molds, yeasts, and bacteria. These infections generally destroy desired flavours and colour and add undesired acetic acid and oxidized flavours. However, the infection of white grapes with the rot fungus called Bortrytis cinerea is very useful. Infection of white grapes with this mold leads to the concentration of the juice in the berry and also gives a characteristic odour to the wine.

The second step in the making of wine is the fermentation of the grapes with various yeasts and lactic acid bacteria. Grapes can be fermented by adding selected wine yeast to dominate the yeast that derive from the vineyard (grape surface, leaves, and stems) and the winery environment (tanks, barrels, hoses). The addition of a selected yeast culture ensures a complete fermentation without the loss of odours and produces a wine of consistent flavour quality. Fermentation temperature and characteristics of the selected yeast determine the amount and type of flavours produced. During spontaneous fermentation, a range of different yeasts grow at different stages of fermentation. Therefore, a winemaker must carefully guide spontaneous fermentations to reduce the risk of spoilage by unwanted microorganisms. Successful spontaneous fermentations can produce very flavourful wines with a range of odour and texture derived from the juice flavours

Followed by yeast fermentation is a second fermentation by lactic acid bacteria. This fermentation is called a malolactic fermentation and during this process, lactic acid bacteria convert malic acid to lactic acid and CO2 , which results in a lowering of the acidity of the wine. The bacteria also change the fruit flavour of wine and add some flavour compounds from their metabolism. Temperature, pH, and availability of other sources of energy affect the rate of malic acid utilization.

After completion of fermentation, wine is clarified by filtration and stabilized. Wine flavours can continue to change while the wine is stored in wooden barrels, stainless steel tanks, and in glass bottles. During this development of wine, various yeasts and bacteria can be present and further modify wine flavours. These yeasts are generally considered spoilage yeasts. Depending on the type of microorganism and on the extent of growth, desirable fruit flavours can be lost by unpleasant odour and taste. Different wines benefit from longer or only short aging.

Answer 3

It turns the yeast and sugar into alcohol.