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Fermentation Process for Beer Making
Yeast
Yeast is a simple micro organism that is classified under the fungi kingdom. Brewers yeast, like all yeast, has the ability to reproduce and grow in environments with or without oxygen. Yeast reproduces more quickly in environments with oxygen, however alcohol is not produced without fermentation which requires an environment that has a low concentration of oxygen through fermentation.
Fermentation
Fermentation is the process by which yeast breaks down sugar molecules, producing alcohol as a byproduct of the reaction.
Oxygen
Oxygen is important in the beginning. The initial supply of oxygen allows the yeast to rapidly multiply and grow. A higher yeast count in the brew will allow for a better and more complete fermentation. Once the yeast depletes the initial supply of oxygen, it will switch reaction pathways and begin to ferment, creating ethanol.
Enzymes
Enzymes help breakdown starches to sugar. When the barley or malt is soaked in water for several days, the grains begin to germinate and produce enzymes. When the germinated grains are dried and crushed, they are called malt. The malt is brewed in water and the enzymes are released to create sugar molecules from the starch in the grains. These sugar molecules are later used as an energy source by the yeast.
Yeast is a simple micro organism that is classified under the fungi kingdom. Brewers yeast, like all yeast, has the ability to reproduce and grow in environments with or without oxygen. Yeast reproduces more quickly in environments with oxygen, however alcohol is not produced without fermentation which requires an environment that has a low concentration of oxygen through fermentation.
Fermentation
Fermentation is the process by which yeast breaks down sugar molecules, producing alcohol as a byproduct of the reaction.
Oxygen
Oxygen is important in the beginning. The initial supply of oxygen allows the yeast to rapidly multiply and grow. A higher yeast count in the brew will allow for a better and more complete fermentation. Once the yeast depletes the initial supply of oxygen, it will switch reaction pathways and begin to ferment, creating ethanol.
Enzymes
Enzymes help breakdown starches to sugar. When the barley or malt is soaked in water for several days, the grains begin to germinate and produce enzymes. When the germinated grains are dried and crushed, they are called malt. The malt is brewed in water and the enzymes are released to create sugar molecules from the starch in the grains. These sugar molecules are later used as an energy source by the yeast.
Sugars
Sugars are used as an energy source for the yeast. The production of alcohol, specifically ethanol, is created through a process which sugar molecules are degraded in an anaerobic environment. The yeast requires a supply of NAD+ (high energy electron transport carrier) to breakdown the glucose to pyruvate. This process is called glycolysis. The NAD+ is an important reactant in glycolysis. It allows for the energy generation phase to begin. The NAD+ phosphorylates the glyceraldehyde 3-phospahte to 1,3-biphospahoglycerate and in the process NAD+ is converted to NADH, which is the activated form of NAD+. This NADH continues on in glycolysis to provide a high energy phosphate transfer to ASP which forms ATP.
CO2 and Alcohol
CO2 and alcohol are byproducts of fermentation. The process by which the NADH is regenerated into NAD+ produces CO2 and ethanol.
Pyruvate, a product of glycolysis, undergoes oxidation and creates CO2 along with acetaldehyde. The CO2 gas released creates an internal pressure and eventually carbonates the beer.
The acetaldehyde continues on in the oxidation reaction process and gains hydrogen ions from the NADH, which regenerates a supply of NAD+. This regeneration of NAD+ from NADH by acetaldehyde creates ethanol as a byproduct.
Sugars are used as an energy source for the yeast. The production of alcohol, specifically ethanol, is created through a process which sugar molecules are degraded in an anaerobic environment. The yeast requires a supply of NAD+ (high energy electron transport carrier) to breakdown the glucose to pyruvate. This process is called glycolysis. The NAD+ is an important reactant in glycolysis. It allows for the energy generation phase to begin. The NAD+ phosphorylates the glyceraldehyde 3-phospahte to 1,3-biphospahoglycerate and in the process NAD+ is converted to NADH, which is the activated form of NAD+. This NADH continues on in glycolysis to provide a high energy phosphate transfer to ASP which forms ATP.
CO2 and Alcohol
CO2 and alcohol are byproducts of fermentation. The process by which the NADH is regenerated into NAD+ produces CO2 and ethanol.
Pyruvate, a product of glycolysis, undergoes oxidation and creates CO2 along with acetaldehyde. The CO2 gas released creates an internal pressure and eventually carbonates the beer.
The acetaldehyde continues on in the oxidation reaction process and gains hydrogen ions from the NADH, which regenerates a supply of NAD+. This regeneration of NAD+ from NADH by acetaldehyde creates ethanol as a byproduct.
Summary of Steps
The brewer starts the yeast with a supply of oxygen so it can rapidly multiply. Once there is sufficient yeast in the brew, the oxygen supply is depleted by the yeast. When the yeast uses all available oxygen, it is forced to metabolize through fermentation. The reactions that comprise fermentation produce the alcohol and the carbonation that makes beer so lovely.
The brewer starts the yeast with a supply of oxygen so it can rapidly multiply. Once there is sufficient yeast in the brew, the oxygen supply is depleted by the yeast. When the yeast uses all available oxygen, it is forced to metabolize through fermentation. The reactions that comprise fermentation produce the alcohol and the carbonation that makes beer so lovely.