Different Types of Fermentations

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Wine is an alcoholic drink that is formed from the fermentation of grapes or grape juice. Wine can be made with other fruits but the true term of the word wine means the fermentation of grapes. To make wine there are many chemical reactions that have to take place in order for the wine to be drinkable. The process of making wine involves a chemical reaction in which sugars are turned to alcohol and carbon dioxide because of the microorganism of yeast. There are also many other chemical processes that affect the outcome of the wine.
An alcohol is a compound that contains an OH group of some kind. For example ethanol, which is produced in the fermentation process, contains an OH group which can be seen in figure 1. Ethanol is also a part of the subgroup called alkanols. Alkanol’s are formed when a hydrogen atom from an alkane compound is replaced with an OH or hydroxyl group (SMITH, 2006) .
To get this alcohol the wine needs to undergo a process called fermentation. Fermentation is a process including a microorganism called yeast breaking down a molecule without using oxygen to produce energy. It is a process in which sugar is consumed by yeast to produce sugar. It can be said that the more sugar there is in the grapes the more alcohol content there will be in the resulting wine. An enzyme in the yeast reacts with the sugar until; the alcohol concentration reaches about 10-14% where the high concentration alcohol kills the yeast and hence stops the process (France, 2014). Fermentation can also occur naturally due to the yeast already in the grapes but takes longer and cannot be controlled (A Taste of Wine).
Belonging to a group of fungi, yeast is a microscopic one-celled organism. Yeasts are found in the soil, water, on the surface...

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...d yeasts. If this is not done the yeasts would compete with one another and the fermentation process would stop prematurely.

There are two different types of fermentation when speaking about the fermentation of yeast in wine, anaerobic and aerobic. Aerobic fermentation is when the feedstock is used for organism growth. It is the process that is in the presence of oxygen and uses it to break down carbohydrates into carbon dioxide to produce energy necessary for its functioning and growth. Anaerobic fermentation is when the yeast or microorganism slightly grows as it converts the feedstock into a metabolite. In wine making it is the process in which the yeast converts the sugar into Ethanol. Anaerobic fermentation occurs in the absence of oxygen when the yeast is able to decompose the sugar and convert it into the ethanol needed in wine production. (SMITH, 2006)

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