Lactic Acid Fermentation: Products, Equation, Examples

What Is Lactic Acid Formation?

Lactic acid fermentation is a crucial metabolic process occurring in some bacteria and in the muscle cells of animals. This is an anaerobic pathway that enables the production of energy in the absence of sufficient oxygen. In particular, it allows the continuation of fast muscle contraction during heavy exercise. To comprehend how organisms adapt to living under changing conditions of oxygen availability, it will be essential to be familiar with how lactic acid fermentation works and its consequences.

Lactic Acid Fermentation

Lactic acid fermentation is a process in which, during anaerobic conditions, the pyruvic acid produced from glucose is converted into lactic acid. This process occurs in the presence of the enzyme lactate dehydrogenase and it involves the reduction of pyruvic acid using NADH as a reducing agent. This process has a pretty low total energy yield; less than seven per cent of the energy from the glucose is released.

Anaerobic Respiration

Anaerobic respiration represents cellular respiration without oxygen. There are two major pathways of such respiration: lactic acid fermentation and alcoholic fermentation. During the process of lactic acid fermentation, glucose turns into lactic acid in organisms. On the other hand, during alcoholic fermentation, pyruvic acid is converted into ethanol and carbon dioxide.

Overview Of Fermentation

Fermentation primarily takes place in yeast and bacteria. However, it can also take place in animal muscle cells when they work anaerobically. Fermentation represents the incomplete oxidation of glucose in yeast, which produces CO2 and ethanol as the products. However, lactic acid fermentation in some bacterial organisms is characterized by the fermentation of pyruvic acid into lactic acid.

Steps Of Lactic Acid Fermentation

The major steps of lactic acid fermentation are as follows:

1. Glycolysis: First, the six-carbon glucose molecule is converted to glyceraldehyde 3-phosphate and then to 3-phosphoglyceric acid.

2. NAD+ Reduction: In these two reactions, the NAD+ is reduced to the reducing agent NADH.

3. Formation of Pyruvic Acid: The 3-phosphoglyceric acid is further converted to phosphoenolpyruvic acid, which then undergoes reduction to form pyruvic acid.

4. Conversion to Lactic Acid: The pyruvic acid, in turn, is converted into lactic acid by using NADH, which, during this process, is reoxidized back into NAD+. In the said reaction, two molecules of pyruvic acid get converted into two molecules of lactic acid. Uses of Lactic Acid Fermentation

The significant applications of lactic acid fermentation are in the food industry, particularly in food preservation and production. The bacteria usually used is Lactobacillus, which helps to create all these different fermented products like pickles, sour beer, fermented fish, and yoghurt. The effects of preservation resulting from lactic acid prevent the growth of spoilage organisms and pathogens in these products.

Health Implications

Though lactic acid fermentation is quite useful in food production, too much lactic acid in muscle cells as a result of intense exercise might be responsible for muscle cramps and discomfort. It builds up in cases where the oxygen supply is inadequate, initializing the anaerobic respiration and consequently the production of lactic acid.

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