How is citric acid monohydrate produced?
As a trusted citric acid monohydrate supplier, I'm often asked about the production process of this widely-used compound. Citric acid monohydrate is a common ingredient in various industries, including food and beverage, pharmaceuticals, and cosmetics. In this blog post, I'll take you through the detailed production process of citric acid monohydrate.
1. Raw Materials
The production of citric acid monohydrate starts with the selection of appropriate raw materials. The most commonly used raw materials are carbohydrates, such as molasses, corn starch, and sucrose. These carbohydrates serve as the source of carbon for the microorganisms that will produce citric acid through fermentation.
Molasses, a by - product of the sugar industry, is a popular choice due to its relatively low cost and high sugar content. Corn starch is also widely used, especially in regions where corn is abundant. It needs to be hydrolyzed into simple sugars before fermentation. Sucrose, which can be obtained from sugar cane or sugar beets, is a pure and easily fermentable raw material, but it is generally more expensive than molasses and corn starch.
2. Fermentation
The fermentation process is the core step in the production of citric acid monohydrate. The selected raw materials are first prepared into a suitable medium, which is then sterilized to eliminate any unwanted microorganisms. After sterilization, the medium is inoculated with a specific strain of microorganism, usually Aspergillus niger, a filamentous fungus.
Aspergillus niger has the ability to convert carbohydrates into citric acid under specific environmental conditions. The fermentation process is carried out in large fermentation tanks, where temperature, pH, and oxygen levels are carefully controlled. The ideal temperature for the growth of Aspergillus niger and citric acid production is around 30 - 32°C, and the pH is maintained at around 2 - 3. Adequate oxygen supply is also crucial for the aerobic fermentation process.
During fermentation, the microorganisms consume the carbohydrates in the medium and produce citric acid as a metabolic by - product. The fermentation process usually takes several days to complete, depending on factors such as the type of raw material, the strain of microorganism, and the fermentation conditions. Once the fermentation is finished, the broth contains a mixture of citric acid, residual nutrients, and microbial cells.
3. Separation and Purification
After fermentation, the next step is to separate and purify the citric acid from the fermentation broth. The first step in this process is the removal of microbial cells and other solid impurities. This is usually done through filtration or centrifugation. Filtration can be carried out using various types of filters, such as diatomaceous earth filters or membrane filters, to separate the solid particles from the liquid broth.
Once the solid impurities are removed, the liquid broth is then subjected to a series of purification steps. One of the most commonly used methods is precipitation. Calcium hydroxide is added to the broth, which reacts with citric acid to form calcium citrate precipitation. The calcium citrate precipitate is then separated from the liquid by filtration and washed to remove any impurities.
After that, the calcium citrate is converted back to citric acid by treating it with sulfuric acid. This reaction produces citric acid and calcium sulfate, which is insoluble and can be removed by filtration. The resulting citric acid solution still contains some impurities, such as colorants and trace metals. To further purify the citric acid, the solution is usually passed through activated carbon columns to remove color and some organic impurities, and then through ion - exchange resins to remove trace metals and other ionic impurities.
4. Crystallization
The purified citric acid solution is then concentrated to a certain degree by evaporation. This increases the concentration of citric acid in the solution and promotes crystallization. During the crystallization process, the citric acid molecules in the solution start to form crystals. The crystallization conditions, such as temperature and cooling rate, are carefully controlled to ensure the formation of high - quality citric acid monohydrate crystals.
Citric acid monohydrate crystals are formed when one molecule of citric acid combines with one molecule of water. The crystals are usually separated from the mother liquor by centrifugation or filtration. The separated crystals are then washed with a small amount of cold water to remove any adhering mother liquor and dried to a suitable moisture content. The dried citric acid monohydrate crystals are the final product, which can be packaged and shipped to customers.
5. Quality Control
Throughout the production process, strict quality control measures are implemented to ensure that the final product meets the required standards. Quality control starts from the selection of raw materials. The raw materials are tested for their purity, sugar content, and other relevant parameters to ensure that they are suitable for fermentation.
During fermentation, the fermentation broth is regularly sampled and analyzed to monitor the growth of microorganisms, the production of citric acid, and the changes in environmental conditions. After purification and crystallization, the citric acid monohydrate product is tested for various quality indicators, such as purity, moisture content, acidity, and heavy metal content. Only products that meet the strict quality standards are allowed to be sold.
Why Choose Our Citric Acid Monohydrate?
As a professional citric acid monohydrate supplier, we have years of experience in the production and supply of high - quality citric acid monohydrate. Our products are produced using advanced production technology and strict quality control measures, ensuring that they meet the highest industry standards.
We offer a wide range of citric acid monohydrate products to meet the different needs of our customers. Whether you are in the food and beverage industry, the pharmaceutical industry, or the cosmetics industry, we can provide you with the right citric acid monohydrate product.
If you are interested in our Citric Acid Monohydrate products, please feel free to contact us for more information and to discuss your procurement needs. Our professional sales team is ready to provide you with the best service and support.
References
- Roehr M, Kubicek CP, Kominek J, et al. Biotechnology of citric acid fermentation. Advances in Biochemical Engineering/Biotechnology. 1992.
- Soccol CR, Vandenberghe LPS, Rodrigues C. Citric acid production. Handbook of Food Fermentations: Technology and Applications. 2017.