Fermentation : Definition, Process, Formula and Application in Industry

What is Fermentation?

Fermentation is the metabolic process of using microorganisms that can help achieve desirable food properties. It is the incomplete oxidation of glucose molecules in the presence of a zymase enzyme in the absence of oxygen outside the cell to produce ethanol (alcohol) or lactic acid and a small amount of energy. Fermentation occurs in some bacteria and unicellular yeasts. The branch of science that studies fermentation is called Zymology. Alcohol, wine, bread, etc., are made in this process. French chemist Louis Pasteur (Louis Pasteur, 1865) described the yeast fermentation process in 1865 and called it oxygen-free respiration. By respiration and fermentation, a lot of things can be done in industries and at home too. The processes are very useful.

It can also change food and beverages by increasing flavor, preserving foodstuffs, providing health benefits, etc. Fermentation is an anaerobic system that can help to make food more nutritious and digestible.

From the Latin verb “fervere,” which means “to boil,” Fermentation comes, but it is the process that can be occurred without heat. It is also a chemical process through which glucose molecules are broken down. At least 10,000 years old, Fermentation occurred during the manufacturing of wine and beer. In the 19th century, Louis Pasteur first used this fermentation term to signify that living organisms open with it.

Different Types of Fermentation:

Microbes specialize in moving particular elements into others to generate various foodstuffs and beverages. There are three different types of Fermentation. They are-

Lactic acid fermentation

Strains of yeast and bacteria can alter starches or sugars into lactic acid. There is no need to heat the process, and it’s an anaerobic chemical process. It is essential for generating cheap foods like pickles, sauerkraut, kimchi, and yogurt.

Ethyl alcohol fermentation

This is done in just two steps. In the first step, pyruvic acid releases one molecule of CO₂ to produce acetaldehyde under the action of the carboxylase enzyme. In the second step, alcohol dehydrogenase takes two hydrogens from acetaldehyde, NADH + H⁺, to produce ethanol (ethyl alcohol), and NAD is released. This process occurs in yeast and some bacteria. 

NADH + H⁺ produced in glycolysis in respiration is consumed in this case. So, the only source of energy in respiration is the two ATP produced by glycolysis. Two ATPs ultimately yield 10 × 2 - 20 kcal of energy. 

Yeast fungi are opportunistic anaerobic fungi. When it reverts from respiration to fermentation, it metabolizes glucose 18 times faster for the same amount of energy. Glycolysis slows down when re-aerobic. The decrease in glycolysis due to the return to aerobic respiration is called the Pasteur Effect. 

Acetic acid fermentation

Acetic acid fermentation is used to produce any vinegar—for example, apple cider vinegar, wine vinegar, etc. Here starch or sugar from grain or fruit ferment into sour testing vinegar.

What Happens During Fermentation Process?

Fermentation can occur in the presence of favorable microorganisms such as molds, bacteria, yeasts, and the absence of oxygen.

• During Fermentation, some cells ferment pyruvate to alcohol and carbon dioxide.
• Cells convert NADH to NAD+, bypassing high-energy electrons back to pyruvic acid.
• From NADH, hydrogen ions and electrons are used to convert pyruvate.
• Then allows glycolysis to continue generating a steady supply of ATP.

How does Fermentation work?

Microbes can stay by using carbohydrates like glucose for energy and fuel. When needed for this energy for the body, organic chemicals ATP Adenosine Tri Phosphate can deliver this energy to every part of a cell. For generating ATP, our body cells and microbes use respiration, an aerobic process that requires oxygen. It begins with glycolysis, and in this process, glucose is altered into pyruvic acid, which takes place in aerobic respiration.

Fermentation is anaerobic respiration without needing enough oxygen to occur in this process. Unlike respiration, Fermentation constructs various organic molecules like lactic acid that produce ATP.

Emerging in environmental circumstances, microbes and cells can change this different mode of energy production.

Stages of Fermentation: Fermentation can have several stages depending on Fermentation. They are-

Primary Fermentation: Microbes can rapidly work with primary ingredients like vegetables and fruits. The presence of the microbes can prevent putrefying bacteria from colonizing the food. It can alter carbohydrates into alcohol and acids.

Secondary Fermentation: It is a long stage of the fermentation process of several days. Here increasing alcohol levels decreases the microbes, which means it starts to die off, and food sources become rare. Different pH levels can affect the chemical reactions between microbes and the environment.

We should follow some tips for starting Fermentation.

These tips are-

• At first, we should establish a starter culture because it is already rich in beneficial microbes.
• To prevent harmful bacteria, it is essential to clean all equipment.
• Avoid exposure to the ferment in the air, which can prevent the risk of spoilage.
• Can submerge this process in a salt solution that is called brine.
• To prevent air contamination should keep the fermenting product in a container.
• Microbes work well at room temperature. By controlling the temperature, it’s possible to manage a good fermentation process.

Advantages of Fermentation:

There are some advantages of this fermented food. Such as-

1. Fermentation can provide a rapid burst of ATP in muscle cells where oxygen is in limited supply.
2. Fermented foods are more nutritious.
3. It can preserve for a long time.
4. It can provide enzymes that are essential for digestion.
5. These are rich in probiotics (beneficial microorganisms).

Besides advantages, there are disadvantages, like hazardous metabolites can survive in fermented foods.

 Overall it can be an alternative to traditional chemical synthesis. Mainly Fermentation is used on a large scale, that is, in the industrial sector. Here it is used to make wine, beer, bread, cheese, vinegar, and other products.

Application/Uses of Fermentation

In the bakery industry

The yeast fermentation process is used in this industry. Bread is made by adding yeast to flour-sugar. CO2 and ethyl alcohol are formed as a result of fermentation of yeast mixed with ingredients such as flour-sugar. The bread puffs up under the pressure of CO2 gas, and the alcohol evaporates in the heat.

In Brewery

Alcohol is produced using yeast fermentation. Grape juice in this process. Wine is made from, and cider is made from, apple juice.

Preparation of alcohol

Ethyl alcohol is produced by the fermentation reaction of yeast with sugars. Alcohol is produced in this process from Chittagur (molasses) at the Darshana sugar mill. Butanol, propanol, etc., are also prepared in the same process.

 In the milk industry

Lactobacillus Helveticas, Streptococcus lactis, etc. bacteria are mixed with milk to make curd at 37-38°C within 3-5 hours. This is also a result of bacterial respiration. The same process is used to make cheese and butter.

In the Ayurvedic drug industry

In preparation for many Ayurvedic drugs, the mixture of various drugs is covered with chitagur (even kept underground for some time). In this, alcohol is prepared from chitagur so that the alcohol absorbs the medicinal properties of various drugs.

In tea, tobacco, and coffee processing

Bacteria called Bacillus megatherium is used in the fermentation process in tea and tobacco processing, and the green leaves are copper colored and aromatic. It also has applications in the coffee industry.

In the meat and fish industry

Various yeasts, some fungi (Penicillium, Aspergillus), and bacteria (Pedi coccus cerevisiae, Bacillus sp.) are produced using fermentation processes, such as Curedham in South America and Katsuobushi fish made in Japan, etc. In this process, yeast produces thiamin and riboflavin in the production of vitamins B and B2.

Production of Vinegar

Ethyl alcohol is produced by mixing yeast with molasses. Acetobacter Aceti bacteria produce acetic acid or vinegar by oxidation. 

In the soft drink industry

The citric acid fermentation process produces the main ingredient of various soft drinks.

In the leather industry

In the leather industry particular type of bacteria (Bacillus subtilis) is used to remove animal hair from leather and separate fat and other tissues. As a result of the fermentation of these bacteria, hair, fat tissue, etc., are removed from the skin.