Citric Acid Production Process: From Microbe to Industry

Citric acid, known for its acidic taste and multiple applications, is one of the most important organic acids in the food, pharmaceutical and cleaning industries. Although it is naturally present in citrus fruits, its industrial production uses a highly controlled fermentation-based process, which allows it to meet the high global demand. In this note, we will explore the fundamental stages of the citric acid production process and its impact on sustainability and industrial innovation.

1. Selection of raw material

The citric acid production process begins with the selection of raw materials rich in sugars, which are the basic substrate for the growth of acid-producing microorganisms. The most common raw materials include:

Molasses: Byproduct of the sugar industry.
Glucose syrups: Derived from corn or sugar cane.
Hydrolyzed starch: Transformed into simple sugars for fermentation.

The quality of raw materials is essential to ensure optimal performance in subsequent stages.

2. Substrate Preparation

Raw materials are prepared for use in the fermentation process. This includes:

Filtration: To remove impurities and unwanted particles.
Sterilization: To ensure a contaminant-free environment and prevent the growth of unwanted microorganisms.
pH adjustment: To optimize the conditions of the growing medium and promote the production of citric acid.

This stage is key to ensuring the efficiency and purity of the fermentation process.

3. Fermentation

Fermentation is at the heart of the citric acid production process. This step uses microorganisms such as Aspergillus niger , a fungus that converts sugars into citric acid in a controlled environment.

Controlled conditions: Parameters such as temperature, pH and oxygen supply are monitored to maximize production.
Duration: Fermentation typically lasts between 5 and 10 days, depending on the conditions and design of the process.

The citric acid produced accumulates in the culture medium, which is then processed for recovery.

4. Separation and Purification

After fermentation, the culture medium contains citric acid along with microorganism cells and other by-products. To recover citric acid, the following steps are carried out:

Filtration: To remove microorganism cells and insoluble particles.
Chemical precipitation: Calcium hydroxide is added to form calcium citrate, which is insoluble and easily separated.
Reaction with sulfuric acid: Calcium citrate is converted back to pure citric acid.

These steps ensure a high purity final product, suitable for its various applications.

5. Concentration and Crystallization

Purified citric acid is concentrated by evaporation to reduce the water content. It then undergoes a controlled crystallization process, where the citric acid solidifies into crystals.

Citric acid forms: It can be produced as anhydrous citric acid or citric acid monohydrate, depending on market needs.
Collection: The crystals are separated from the remaining liquid by centrifugation or filtration.

6. Drying and Grinding

Wet citric acid crystals are dried to remove residual moisture and ensure product stability during storage. In some cases, dried citric acid is ground to obtain a uniform particle size suitable for final application.

7. Packaging and Storage

Finished citric acid is packaged under controlled conditions to protect it from moisture and ensure its quality during storage and transport. Packaging formats include:

Sacks or bags for industrial use.
Small packaging for food and household applications.

The packaged product is stored in dry, well-ventilated areas, ready for distribution.

8. Distribution and Final Use

Citric acid is distributed to a wide variety of industries, where it is used in applications such as:

Food: Preservatives, acidulants and flavour enhancers in beverages, sweets and canned products.
Pharmaceutical: pH regulation in medications and vitamin supplements.
Cleaning products: Eliminating limescale residues and improving the effectiveness of detergents.
Cosmetics industry: Formulation of personal care products.

Its versatility makes it an essential product for numerous sectors.

Commitment to Sustainability

Citric acid production is a process that has been adapted to minimize its environmental impact. Sustainable initiatives include:

Use of renewable raw materials: Such as molasses and starch from local sources.
Recycling of by-products: Use of fermentation waste for animal feed or fertilizers.
Energy optimization: Efficient fermentation and evaporation technologies to reduce energy consumption.

These practices reflect the industry's commitment to sustainable development and the circular economy.

Conclusion

The citric acid production process is a perfect example of how biotechnology transforms natural resources into a versatile product essential for modern life. Every stage, from raw material selection to distribution, is designed to ensure a high-quality, safe and sustainable product.

At Acciomate Engineering & Projects , we offer engineering and project services that optimize each stage of this process, helping companies in the chemical sector to improve their efficiency, sustainability and competitiveness in a global market.