Fermentation is a process used to produce wine, beer, yogurt and other products. Here"s a look at the chemical process that occurs during fermentation.

Fermentation Definition

Fermentation is a metabolic process in which an organism converts a carbohydrate, such as starch or a sugar, into an alcohol or an acid. For example, yeast performs fermentation to obtain energy by converting sugar into alcohol. Bacteria perform fermentation, converting carbohydrates into lactic acid. The study of fermentation is called zymology.

History of Fermentation

The term "ferment" comes from the Latin word fervere, which means "to boil." Fermentation was described by late 14th century alchemists, but not in the modern sense. The chemical process of fermentation became a subject of scientific investigation about the year 1600.


Fermentation is a natural process. People applied fermentation to make products such as wine, mead, cheese, and beer long before the biochemical process was understood. In the 1850s and 1860s, Louis Pasteur became the first zymurgist or scientist to study fermentation when he demonstrated fermentation was caused by living cells. However, Pasteur was unsuccessful in his attempts to extract the enzyme responsible for fermentation from yeast cells. In 1897, German chemist Eduard Buechner ground yeast, extracted fluid from them, and found the liquid could ferment a sugar solution. Buechner"s experiment is considered the beginning of the science of biochemistry, earning him the 1907 Nobel Prize in chemistry.

Examples of Products Formed by Fermentation

Most people are aware of food and beverages that are fermentation products, but may not realize many important industrial products results from fermentation.

Ethanol Fermentation

Yeast and certain bacteria perform ethanol fermentation where pyruvate (from glucose metabolism) is broken into ethanol and carbon dioxide. The net chemical equation for the production of ethanol from glucose is:

Ethanol fermentation has used the production of beer, wine, and bread. It's worth noting that fermentation in the presence of high levels of pectin results in the production of small amounts of methanol, which is toxic when consumed.

Lactic Acid Fermentation

The pyruvate molecules from glucose metabolism (glycolysis) may be fermented into lactic acid. Lactic acid fermentation is used to convert lactose into lactic acid in yogurt production. It also occurs in animal muscles when the tissue requires energy at a faster rate than oxygen can be supplied. The next equation for lactic acid production from glucose is: