What is Fermentation? What are the Types of Fermentation Processes?


Fermentation is a naturally effective tool that helps in making the food more nutritious, digestible and tasty. 

The fermentation process is used to produce beer, yogurt, wine, and other several products. 

Fermentation is considered as a metabolic process where an organism is converted into a carbohydrate such as into sugar or starch, or alcohol or an acid. The process is performed by bacteria and microbes that convert carbohydrates into different types of acids. These different types of acids are:

  1. Alcoholic Fermentation
  2. Lactic Acid Fermentation

The study of fermentation is called zymology also known as zymurgy, which studies the biochemical processes and its practical uses.  

In this article, we will discuss the history of fermentation along with its examples, types, and differences. 


By the late 14th century, the alchemists described the process of fermentation. Later, the chemical process of fermentation became a topic of scientific investigation in the mid-1600s. 

The process of fermentation was not described in a modern sense but was still used to make cheese, wine, beer before many people understood it. In the 1850s, Louis Pasteur demonstrated that fermentation is caused by living cells. He was the first zymurgist to study fermentation. However, he failed in his attempts to try fermentation with yeast cells.

Eduard Buechner, a German chemist played his role. He concluded that fluid can be extracted from yeast cells to ferment a sugar solution. His experiment was considered as the beginning of fermentation research and development in biochemistry and earned him a Nobel Prize.  

Types of Fermentation:


  • Lactic Acid Fermentation


In the process of lactic acid fermentation, the NADH molecule transfers its electrons into pyruvate which generates lactate. Lactate is a deprotonated form of lactic acid. 

The bacteria in the yogurt carry lactic acid fermentation as well as the red blood cells in the human body. It also occurs in muscles when the tissues require energy and have low oxygen levels. For example, when anaerobic respiration takes time to get normal after a workout.

The lactic acid produced by muscle cells is transported to the liver through the bloodstream. Then lactate is converted back into pyruvate where it’s processed normally for cellular respiration.


  • Alcoholic Fermentation


In the process of alcoholic fermentation, the NADH molecule also donates its electrons to pyruvate which forms ethanol. This a two-step process. Firstly a carboxyl group is removed from pyruvate to release carbon dioxide, which produces a molecule called acetaldehyde. Secondly, NADH transforms its electrons to acetaldehyde to form ethanol.  

Yeast performs the alcoholic fermentation process which produces ethanol and then alcoholic drinks such as wine, beer, and whiskey. However, it is poisonous and toxic to yeast microorganisms just like humans. 

Difference between Lactic Acid Fermentation and Alcoholic Fermentation:

Both types of fermentation are produced with the help of the NADH molecule and pyruvate. They are considered the types of anaerobic respiration. 

The main difference between these two is that they produce different items and are required for different needs. The lactic acid fermentation produces lactate molecules whereas alcoholic fermentation produces ethyl or ethanol molecules including carbon dioxide. 

Lactic acid fermentation occurs in muscles and tissues whereas alcoholic fermentation, also known as ethanol fermentation is used in food industries. 

Examples of Fermented Products:

We have mentioned the products below that are created by the process of fermentation of any type: 

  1. Bread
  2. Yogurt 
  3. Cheese
  4. Beer
  5. Wine
  6. Soured items such as pepperoni, kimchi, etc. 
  7. Hydrogen gas
  8. Industrial alcohol e.g. biofuels