ACETIC FERMENTATION: CHARACTERISTICS, APPLICATIONS, EXAMPLES - BIOLOGY - 2025

The acetic fermentation is a chemical process mediated by the action of a group of bacteria belonging to the genus Acetobacter. Through this process, these bacteria act on ethyl alcohol (ethanol), oxidizing it, obtaining acetic acid (CH ₃ COOH) and water (H ₂ O) as final products.

This is a process that is very useful from an industrial point of view, since its main product has various uses in different areas, such as medical, pharmaceutical and gastronomic.

Structure of acetic acid, product of acetic fermentation. Source: No machine-readable author provided. Walkerma assumed (based on copyright claims).

characteristics

The bacteria that carry out the process necessarily require the presence of oxygen to be able to carry it out.

As in any chemical process, acetic fermentation requires a substrate, ethyl alcohol. This is obtained through the alcoholic fermentation process that is also carried out by a microorganism, the yeasts of the genus Saccharomyces. What they do is process the sugars to obtain ethanol (alcohol), carbon dioxide and ATP, all under anaerobic conditions.

This ethanol that is obtained is oxidized by acetobacteria, which in the mandatory presence of oxygen, obtain acetic acid and water as final products, according to the following reaction:

C ₂ H ₅ OH + O ₂ ^Acetobacter CH ₃ COOH + H ₂ O

Once the acetic acid has been obtained, it should not be exposed to the open air, since it can undergo a new chemical transformation, losing its properties.

Aceobacter

The bacteria that carry out the acetic fermentation process belong to the genus Acetobacter, which owes its name to the property they have of oxidizing ethanol to acetic acid.

This is a genus that includes many species, a total of 17, of which the one that is most used for the production of acetic acid is Acetobacter aceti.

This is a gram negative bacterium and belongs to the group of bacilli, as it is rod-shaped. Likewise, for its development it requires certain conditions such as the presence of oxygen, an average temperature of 30 ° C and a pH of 6.0.

products

Acetic fermentation is a complex process that has two products, one of them being more important than the other. That product is acetic acid, also known as ethanoic acid. The other product is water.

The chemical formula for acetic acid is CH ₃ COOH. It is mainly in the solid state, forming crystals. It has a molar mass of 60.05 g / mol and a density of 1.049 g / cm3. Likewise, its melting point is 17 ° C and its boiling point is 118 ° C.

Acetic acid is soluble in various substances such as water, ether, glycerin, acetone, and benzene. It is also capable of dissolving some organic and inorganic compounds by itself.

It is one of the simplest carboxylic acids, which can be deduced from the simplicity of its chemical structure. However, despite this, acetic acid is a product widely used in various areas, such as gastronomy, medicine and chemistry, among others.

Applications

Acetic fermentation is used to produce acetic acid. The applications and uses that can be given to this compound are many.

Medicine

In the medical field, acetic acid has multiple uses. Gynecologists use it in a procedure known as colposcopy to determine the presence of human papillomavirus infection.

Cells infected by the virus react with acetic acid and acquire a whitish color, the test being then positive.

Similarly, acetic acid is used in pathological anatomy laboratories as an element of fixative solutions, which are intended to preserve tissues.

Gastronomy

The uses of acetic acid as vinegar in the gastronomic area are widely known.

First of all it is used as a dressing for salads and dishes based on meat, fish and seafood. Likewise, it is also used as a preservative and is even added to mayonnaise in order to inhibit the growth of bacteria such as Salmonella.

Vinegar is widely used in the gastronomic industry. Source: pixabay.com

Pharmaceutical

Acetic acid is a key ingredient in some products such as sunstroke creams and other medications used to treat conditions such as seborrhea and fungal conditions that settle primarily on the scalp.

Cosmetics

In the cosmetic industry, acetic acid is used as a constituent element in anti-dandruff shampoo and styling creams, as well as in softening masks.

Domestic uses

Housewives tend to use acetic acid as a stain remover on various surfaces. In the same way, it is a powerful disinfectant that is also used especially on kitchen countertops and other places in the home.

Examples

There are numerous examples of acetic fermentation. These depend on the substrate used by Acetobacter. Anything that contains sugars that can be transformed into ethanol and subsequently subjected to fermentation to obtain acetic acid constitutes a good substrate.

This is how a magnificent vinegar can be made from wine, cereals (especially rice), fruits and honey.

Wine vinegar

Wine vinegar is a highly valued product in the gastronomic industry. It is obtained through two consecutive fermentation processes. The first, alcoholic fermentation is carried out by yeasts belonging to the genus Saccharomyces and the second, acetic fermentation, by bacteria of the genus Acetobacter.

This type of vinegar is widely used in cooking recipes as a condiment and is a fundamental part of various dressings.

Likewise, for years it has also been used for its medicinal uses, since it helps regulate the levels of certain elements such as triglycerides and cholesterol.

In the same way, it has very important antioxidant properties, since they prevent cellular aging and the appearance of diseases such as cancer. It also positively intervenes in the functioning of the cardiovascular system.

Fruit vinegar

Fruit vinegar is obtained from any fruit, thanks to the fermentation of the sugars present in them. At first they are converted into alcohol and later, thanks to the action of acetic bacteria, converted into acetic acid.

It can be made from various fruits, the most widely used being apple, tamarind, mango and orange, among others. It has the quality of being less acidic than other types of vinegar, thanks to the characteristic sweetness of the fruits.

Today it is used as a dressing for various dishes such as salads, meat, fish and seafood.

Cereal vinegar

It is obtained through the fermentation of sugars present in cereals. The most used for making vinegar is rice.

Its color varies from white to gold and it has a sweet taste. It is also widely used in Asian cuisine, especially to prepare sushi.

Honey vinegar

It is a little known type of vinegar. When the sugars in honey are fermented, it is transformed into mead and later, by the action of acetic fermentation, it is transformed into honey vinegar.

This vinegar has a very pleasant smell and has a color similar to amber with some bright touches.

Malt vinegar

If honey vinegar is little known, malt vinegar is even less so. This is obtained through the alcoholic fermentation of barley malt and subsequent acetic fermentation.

Malt vinegar is very aromatic, has a bright ocher color and is used by connoisseurs in the preparation of some dishes. In English cuisine it is a must.

References

1. Cox, M. and Nelson, D. (2014). Lehningher's Principles of Biochemistry. Editorial Omega. 6th edition.
2. Jiménez, J., Santos, I and García, I. (2009). Optimization of biotechnological processes. The acetic fermentation. Part I: The proposed model. Biochemical Journal. 45 (1). 1-6
3. Madigan, M., Martink, J. and Parker, J. (1997). Brock biology of microorganism. Prentice Hall International. 8 ^th
4. Silva, M., Torres, A., Silva, W., Silva, F. and Swarnakar, R. (2007). Cashew wine vinegar production: alcoholic and acetic fermentation. Brazilian Journal of Engineering. 24 (2).
5. Wackett, L. (2018). Microbial acid fermentation products. Microbial Biotechnology. 11 (1). 268-269.