Fermentation is the process in which an organism such as bacteria or fungi converts a carbohydrate into alcohol or acid. Chemically speaking, it is a metabolic process in which these organisms break down starch or sugar in order to produce energy. As a result, the matter where they get this starch or sugar undergoes chemical change. This process is well known when it comes to making alcohol such as wine and beer and also for making yogurt, cheese and other products.
Unknown to most people, fermentation itself is a natural process. Before biochemical technology was understood, people had already this process for centuries. During 1850s and ‘60s, Louis Pasteur, who is also known as a famous scientist and inventor, became the first one to study fermentation. His discoveries showed that fermentation was caused by microscopic living cells.
In general, there are two known types of fermentation. Each type was done by a certain microorganism, therefore producing different effects, even though the process itself is more or less the same.
- Ethanol Fermentation is done by yeast and certain bacteria by breaking down pyruvate molecules, a glycolysis or glucose metabolism product into ethanol and carbon dioxide. In a chemical equation, it is usually expressed like this:
C6H12O6 (glucose) → 2 C2H5OH (ethanol) + 2 CO2 (carbon dioxide)
This kind of fermentation is used by people in the production of bread, wine and beer. And also, take note that this fermentation can also result in production of methanol, a toxic kind of alcohol, in small amounts.
- Lactic Acid Fermentation, on the other hand, is done by bacteria by breaking down pyruvate molecules from glycolysis into lactic acid. This kind of fermentation is used to turn lactose into lactic acid in production of cheese and yogurt. Take note also that this kind of fermentation is being performed in animal muscles when the tissue requires energy at a faster rate, especially when the oxygen supply is limited. In a chemical equation, it is expressed like this:
C6H12O6 (glucose) → 2 CH3CHOHCOOH – This is the equation when lactic acid is produced from glucose during glycolysis.
C12H22O11 (lactose) + H2O (water) → 4 CH3CHOHCOOH – This is the equation when lactic acid is produced through fermentation of lactose and water.