Fermentation

Introduction

 Respiration is the process by which organic compounds decompose to release energy in the presence or absence of oxygen. The process of deconstruction of complex sugar molecules into smaller molecules in the absence of oxygen is called fermentation. Since the fermentation process occurs in the absence of oxygen, it is called anaerobic respiration. It is a natural process by which glucose is converted into alcohols and acids with the help of enzymes to release chemical energy and gases.

There are 4 types of fermentation based on the by-product they produce;

• Lactic Acid Fermentation
• Alcoholic Fermentation
• Acetic Acid Fermentation
• Butyric Acid Fermentation

Process of Fermentation

The fermentation process can be understood by the following steps;

1. Glycolysis is the first step. In this step, a sugar molecule containing 6 carbon molecules is broken down into 3-carbon molecules called pyruvate.
2. The second step is the conversion of pyruvate molecules into acetyl coenzymes. These further decompose into simple carbon molecules through the citric cycle in aerobic respiration.

While, in alcoholic and lactic acid fermentation, NADH+H+ acts as a reducing agent, which is oxidised to NAD+ (Nicotinamide adenine dinucleotide). The difference between aerobic and anaerobic processes is that the energy released in anaerobic processes such as alcoholic and lactic acid fermentation processes is not much, and the total sum of ATP (adenosine triphosphate) molecules is produced during fermentation is two, which is very less than compared to aerobic respiration.

Types of fermentation

There are 4 types of fermentation-based on the by-product they produce. They also differ in the catalysts that are used in each process. According to the products, they are used in different industries. They are as follows: 

Lactic Acid Fermentation

In this type of fermentation, sugar is converted into lactic acid by the action of yeast strains or bacteria. The process described above takes place with pyruvate molecules using NADH (Nicotinamide adenine dinucleotide+ Hydrogen) to form lactic acid. Lactic Acid Fermentation is commonly used to make foods such as bread, yoghurt, pickles, etc. 

Alcoholic Fermentation

It is the process of converting sugars into ethyl alcohol and carbon dioxide in the presence of yeast. The bacteria carry out the anaerobic process in their cytosol. Alcohol fermentation is used in the production of alcoholic beverages such as wine and beer. Control of fermentation is a prerequisite to determining the quality of the final product. Fermentation monitoring is a growing need, which calls for fast and low-cost methods to provide real-time information to assure effective control at all stages of the process.

Acetic Acid Fermentation

The raw material in this type of fermentation is starch from grains and fruits. This is fermented into vinegar and various other acetic acids. In recent times, their widest use is in cocoa fermentation, which is the oxidation of ethanol and lactic acid to acetic acid. Acetic acid diffuses into the cotyledons, which undergo a series of biochemical modifications leading to the synthesis of cocoa colour and flavour.

Butyric Acid Fermentation

Such fermentation uses salts instead of sugar. It converts lactate acid into butyric, acetic and propionic acids with the help of a selected bacterial strain such as C. thermoaceticum. Butyric acid has diverse applications in the chemical, food, and pharmaceutical industries. In the chemical industry, it is used in the production of thermoplastics. It is commonly used as a fruit additive in the food industry and food flavours for its butter-like taste. It also plays a significant role in the pharmaceutical industry due to its therapeutic effect in diseases such as haemoglobinopathies, cancer and gastrointestinal diseases.

CONCLUSION

Various kinds of fermentation processes have major industry uses in today’s world. Besides that, a lot of health benefits are associated with fermentation. Fermented foods are more nutritious than their unfermented form. Lactic acid fermentation is used to make daily food products. It also enables the preservation process. Alcoholic fermentation is the basis of the liquor industry and has other beneficial food by-products. Fermented food has been proved to increase immunity as well. It has a positive impact on mental illnesses such as anxiety and depression. It also improves the health of the heart.