How Is Citric Acid Manufactured? Comprehensive Guideline

This article discusses the most intriguing question “How is citric acid manufactured?” Citric acid, a naturally occurring compound, belongs to the chemical family known as tricarboxylic acid and has been extracted from citrus fruits including lemons and limes is commonly used widely in the industries of food and beverages, pharmaceutical industries, and cleaning industries because of its properties of preservation, flavouring, and cleaning.

Understanding Microbial Fermentation in the Production of Citric Acid

The current production of industrial citric acid mainly follows a microbial fermentation process, which involves the use of moulds, including aspergillus niger to transform simple sugars into citric acid. While extraction of citric acid from citrus fruits involves time and money since it is labour intensive microbial fermentation is more viable for large-scale production.

The process of “How is citric acid manufactured?” usually starts with the selection of an appropriate growth medium, more of which can be molasses or glucose, which helps the moulds to grow while at the same time synthesising citric acid.

This medium is inoculated with the Aspergillus niger mould under certain conditions of temperature, pH and oxygen concentrations that are ideal for an optimal fermentation process whereby the mould consumes the sugars present and produces citric acid as a by-product.

Difference Between Submerged Fermentation and Surface Fermentation

When discussing “How is citric acid manufactured?”, two major categories of fermentation occur which are submerged fermentation and surface fermentation. The submerged fermentation that is used involves the use of aspergillus niger mould, where the fermentation occurs in a submerged liquid nutrient medium, commonly in large stirred tank bioreactors under an aerobic environment.

This method is highly recommended in industries because it is less time-consuming and very economical, and it also ensures that the circumstances around the fermentation process are well controlled thereby increasing the yield of citric acid. The second method, though rarely used in the present time, is surface fermentation, where the mould is grown on the top of a solid media-like nutrient solution spread over trays.

The mould grows on the surface, where citric acid is produced in more natural conditions as compared to submerged fermentation. While surface fermentation can also yield a good quality citric acid, it is comparatively less effective and difficult to regulate as submerged fermentation, and for this reason, the surface method has gradually been replaced by the techniques of the submerged method.

Citric Acid Extraction and its Recovery

After the fermentation process is done, a recovery process has to be carried out where the citric acid is separated from the fermentation broth, which contains microbial cells, unutilized sugars, and several other organic substances. The first operation of such extraction normally entails the removal of the mould biomass from the liquid broth by filtration or centrifugation and in return obtains a clarified medium highly concentrated in citric acid.

Further, adjusting the pH of the solution with calcium hydroxide followed by precipitation results in the formation of insoluble calcium citrate, a process known as “lime precipitation”. It is further reacted with sulfuric acid to bring back the soluble citric acid, and any remaining calcium is filtered out in the form of calcium sulfate, commonly known as gypsum, thus purifying the citric acid solution.

The Purification and Crystallization of Citric Acid

After the citric acid has been extracted and recovered in its soluble form, it goes through a process of refining to eliminate any undesired impurities to meet the quality levels that are acceptable to many industries. This purification process normally consists of several stages of ion exchange, activated carbon, and evaporation to form or concentrate the citric acid solution.

Lastly, the obtained citric acid is purified and undergoes a crystallization process where the solution is cooled, resulting in the formation of solid citric acid. From this liquid, the citric acid crystals are passed through filtration or centrifugation and washed to expel the rest of the impurities and then dried to provide the final citric acid product in the form of crystals, which are ready for packaging for use in different industries.

Conclusion

To sum up, the process of “How is citric acid manufactured?” includes microbial fermentation and subsequent processes such as extraction, purification and crystallization and all of them are directed to obtain high-quality citric acid for different applications. In the future, as technology develops, advancements in citric acid manufacturing can make it more environmentally friendly and efficient in production, ensuring its continuous importance in various industries.