How is Citric Acid Made? Overview

This article focuses on the rather interesting topic of “How is citric acid made?” including the natural and traditional ways of obtaining the substance as well as the modern commercial methodologies that have emerged due to the constant increase in the global consumption of citric acid. This compound is used in food industries, pharmaceutical industries, and cosmetic industries since it has properties such as acting as a preservative as well as having an acidifying effect when used in foods.

Natural Process of Extracting Citric Acid

It is however important to note that citric acid can be extracted from citrus fruits like lemons, limes, oranges, and grapefruits, but this method is not widely used industrially today because of some challenges that are associated with this method, including that citric acid from natural sources does not yield a lot and the process of fermenting and purifying the acid is cumbersome compared to the modern industrial methods.

This method is well suited for home use, or citric acid is then produced through the process involving either the juice, which is treated with calcium hydrogen oxide to precipitate calcium citrate, which is then filtered and treated with sulfuric acid to produce the citric acid that can be crystallized from solution and purified and dried, to obtain the final product.

Citric Acid Commercial Production

The commercial production of citric acid has changed its natural extraction methods, which are slow and low-yielding, with a faster and better-yielding microbial fermentation process for large-scale production. This method is not only suitable for providing a more stable and quality citric acid supply but also suitable for producers to meet the quality demand from different industrial uses.

The main microorganism used in this fermentation process is a fungus called Aspergillin niger, which is preferred for this purpose due to its high citric acid production coupled with its utility in simple and cheap carbohydrate sources like molasses, glucose syrup, or other carbohydrates from corn or beet.

The Fermentation Process

As a part of a discussion about “How is citric acid made?”, the fermentation involves several steps; the first of which involves the preparation of a suitable growth medium, which is often a carbohydrate source, for example, glucose or sucrose, a nitrogen source, for instance, ammonium salts and several minerals that facilitate the growth of aspergillus niger. After preparation of the growth medium, it is then sterilized to remove other microorganisms that may interfere with the growth of the aspergillus niger.

After sterilization, the basal medium is inoculated with spores of aspergillus niger, and the fermentation process starts under optimum conditions of temperature, pH, and aeration to maximize citric acid production by the fungus. Normally this process is conducted in large fermenters that contain provisions for stirring, aeration, temperature, and pH recording.

Optimization of Fermentation Conditions

High yields of citric acid require that strict fermentation conditions be maintained and fine-tuned, which include the desirable low pH, mostly between 2.0 and 3.5 because lots of citric acid is produced by aspergillus niger under these conditions of low pH.

Also, the temperature is often kept at about 25-30 degrees Centigrade to support good growth and metabolism of the fungus. Another concerning factor about the question “How is citric acid made?” is the control of aeration since oxygen is essential for the breakdown of carbohydrates by the selected fungus aspergillus niger and the subsequent formation of citric acid.

If aeration is too little, it will result in low yields as well as the formation of unwanted products; if aeration is too much, it creates problems such as foaming. Besides, it is important to maintain the levels of dissolved metal ions, particularly the active iron, manganese, and zinc ions in the growth media, because these ions influence the activity of the enzymes from the citric acid metabolic route.

Application of Citric Acid in the Industries

Fermented citric acid is versatile and used in different industries, as it is used as a flavouring agent to give a sour taste to foods and drinks and as an anti-microbial agent, which prevents the growth of microbes that cause food spoilage. Fermented citric acid also works as an antioxidant, which prevents the oxidation of fats and oils used in the food industry.

In the pharma field, citric acid finds its use as a diluent in the formulation of tablets, and also as a stabilizing agent in some fluid preparations and also as an acidifying agent. Also, citric acid serves as an additive to cosmetic products such as scrubs, where it serves as an ingredient to eliminate dead cells and also helps in controlling the pH of the cosmetic creams and lotions for effectiveness.

Conclusion

Beginning with the extraction of citric acid from citrus fruits, the method of “How is citric acid made?” has come a long way. Fermentation is now used for large-scale production of this compound. By understanding the intricate processes involved in its production, one can better appreciate the scientific significance of this compound, which is so vital in today's society.