How is citric acid made? A comprehensive guide

Citric Acid Is Made How? A Comprehensive Guide

Citric acid is an organic compound widely used in food, cosmetics, medicine and industrial fields, and its chemical name is 2-hydroxypropane-dicarboxylic acid. It not only has a sour taste, but also has a variety of functional properties, such as chelation and pH adjustment ability. With the growth of market demand, the production technology of citric acid is also developing. This article will explore in detail the citric acid manufacturing process, from raw materials to the final product of each step.

1. Citric Acid Overview

Citric acid is a colorless crystal or white powder, slightly soluble in cold water, soluble in hot water. It was originally isolated from lemon juice, hence the name. In modern industrial production, citric acid is mainly produced by fermentation, rather than directly extracted from natural fruits. This method is not only cheaper, but also mass-produced.

2. Citric acid raw materials and strain selection

The production process of citric acid mainly depends on fermentation technology, and the core of fermentation is the cultivation of microorganisms. Commonly used species include Aspergillus niger (Aspergillus) and Trichoderma viride (Penicillium notatum). These microorganisms are capable of converting carbohydrates, such as glucose, to citric acid.

When selecting raw materials, manufacturers often use starchy substances such as corn starch, tapioca starch or sugar cane juice. These substrates are inexpensive and readily available, making them suitable for large-scale production. Glucose in the substrate is the key carbon source for microbial fermentation.

3. Citric acid fermentation process

Fermentation is the core step of citric acid production. The following are the main steps of the fermentation process:

1. Sterilization: Before fermentation, the medium needs to be sterilized at high temperature to eliminate the possibility of bacterial contamination. This is a key step in ensuring a smooth fermentation.

2. Inoculation: Inoculate the selected species into a bactericidal medium. After inoculation, the microorganism begins to grow and metabolize the glucose in the substrate, producing citric acid.

3. Fermentation conditions control: The fermentation process requires strict control of temperature, pH and dissolved oxygen levels. Typically, the fermentation temperature is controlled at 25-35°C and the pH is between 4.5-5.5. Through stirring and aeration, a sufficient supply of oxygen can be ensured, and the growth of microorganisms and the production of citric acid can be promoted.

4. Fermentation time: Depending on the strain and substrate, the fermentation time is usually between 48-72 hours. During this time, the microorganisms will convert most of the glucose to citric acid, while producing a small amount of by-products.

4. Citric acid extraction and refining

At the end of the fermentation, the product needs to be extracted and refined to obtain high-purity citric acid.

1. Filtration and centrifugation: The fermentation broth needs to be filtered and centrifuged to remove bacteria and other solid impurities. This step can significantly improve the efficiency of subsequent processing.

2. Acid-base neutralization: By adjusting the pH, citric acid can be precipitated from the solution. Typically, citric acid is precipitated as a salt by the addition of an alkaline material such as lime.

3. Ion Exchange and Crystallization: The citric acid was further purified by ion exchange resin to remove impurities. Through the crystallization process, the citrate salt is converted to the free acid to obtain high purity citric acid crystals.

5. Citric acid application field

The versatility of citric acid makes it widely used in many fields:

1. Food industry: Citric acid is commonly used in food additives, as a sour agent, preservative and chelating agent. It can extend the shelf life of food and prevent discoloration caused by metal ions.

2. Cosmetics and personal care products: Citric acid is used to adjust the pH and has a certain antioxidant effect. It is also used as an exfoliant to help remove dead skin cells.

3. Pharmaceutical field: Citric acid is used as a pharmaceutical excipient in the pharmaceutical industry to help regulate the pH and stability of drugs.

4. Industrial applications: Citric acid can be used in water treatment, metalworking and cleaning products as a chelating and acidifying agent.

6. Citric Acid Production in the Future

With the enhancement of environmental awareness, green manufacturing and sustainable development have become an important direction of citric acid production. Researchers are developing more efficient and environmentally friendly production processes, such as using renewable resources as substrates and optimizing fermentation conditions to reduce energy consumption.

Advances in biotechnology have also opened up new possibilities for the production of citric acid. Through genetic engineering, scientists can improve the metabolic pathway of the strain and increase the yield and production efficiency of citric acid.

Conclusion

The manufacturing process of citric acid involves multiple complex steps, from the selection of raw materials to fermentation, extraction and refining, each of which requires precise control. With the continuous progress of technology, the production efficiency and product quality of citric acid will be further improved to meet the market demand for diversified products. If you have more questions about the manufacturing process of citric acid, welcome to explore further!