At a Glance:
Citric acid is an organic acid naturally occurring in food and drinks and in industrial uses. It is manufactured mainly through microbial fermentation by fungi such as Aspergillus niger. Submerged, surface, and solid-state fermentation are significant techniques in fermenting it. The industry is increasingly looking at sustainable methods in terms of raw materials that are renewable and to improve the microbial strains to give better productivity with minimal impact on the environment as demand increases.
How Citric Acid is Produced – An Introduction
Citric acid is a vital organic acid in the food and pharmaceutical industries. It occurs naturally in citrus fruits such as lemons and oranges. However, its significance extends beyond this since it represents one of the most important steps known as the citric acid cycle products (Krebs cycle), through which energy is produced within living organisms. Its applications range from flavor enhancement to food preservation and industrial use such as removal of rust. Because of its nontoxicity and multidimensional efficiency, the annual global demand for citric acid already exceeds 2.8 million tons.
Citric acid is also extensively used in cosmetic, chemical, and detergent products. Because it can form chelates with a number of metals and therefore is widely used as a sequestrant, an antibacterial agent, and in cleaning agents for its ability to remove mineral deposits, it is probably one of the most versatile acids in the world. It is thus one of the widely produced organic acids globally, with applications across various fields.
How Citric Acid is Produced in Industrial Capacity?
Microbial fermentation has become the process of choice today due to its great efficiency and scalability, while it is also more cost-effective. Extraction from natural sources has become largely non practical to fulfill industrial-scale production requirements. So this is how citric acid is produced to meet industrial demands:
Important Producers for Citric Acid
Aspergillus niger
- A filamentous fungus, recognized for its capacity to produce large amounts of citric acid from inexpensive substrates, such as molasses or starch is used.
- It is preferred because it has robust performance, resistance to contamination, and tolerance of acidic conditions.
Yarrowia lipolytica:
- A yeast with emerging potential for the production of citric acid is commonly utilized in specialized applications.
- This yeast is useful since it converts lipids into citric acid. Therefore, it is a good candidate for specific production processes where substrates are oil-based and abundant in that area.
Bacterial Strains:
Corynebacterium glutamicum has the ability to produce amino acids apart from citric acid, under specific conditions.
Fermentation Technologies:
There are three primary fermentation technologies used in industrial production:
SmF: Submerged Fermentation.
It accounts for the majority of the world’s market share.
Fungal growth in liquid medium under controlled conditions – temperature, pH, and oxygen supply.
- Advantages: High yield, potential automation, and product quality consistency.
- Challenge: Energy and water-intensive, generating a lot of wastewater.
In SmF, the main issue is to regulate oxygen transfer rates to avoid microbial stress and optimize acid production.
SSF: Solid-State Fermentation
Makes use of solid substrates, such as agricultural residues (sugarcane bagasse, coffee husks).
- Advantages: Utilizes waste material and uses water minimally.
- Challenge: Harder to scale and automate than SmF.
Generally, SSF finds more practice in areas that generate large amounts of agricultural waste products, and it can provide an alternative perceived as environmentally friendlier.
Surface Fermentation:
Traditional technique in which the fermenting microorganisms grow at the surface of a solid or semisolid substrate
- Advantages: Operates on simple principles, requires no elaborate equipment
- Challenges: Very labor-intensive and not as efficient as modern techniques
Even though surface fermentation is not easily used in large-scale industrial production due to very high labour costs, it does have applicability in small-scale production in specific areas.
Also Read: Where Does Vanilla Extract Come From? The Truth About Beaver Goo and Vanilla Flavor
How Citric Acid is Produced: Detailed Production Process
Substrate Preparation:
The base is usually a sugary material, such as glucose, molasses, or corn steep liquor. Residues from agro-industries are being increasingly employed for more environmentally friendly production and lower costs.
The raw materials are first sterilized to eliminate undesirable bacteria before starting the fermentation process. The composition may be manipulated based on the substrate used to maximize the growth of the organism that produces citric acid.
Inoculation and Fermentation:
- Microbial cultures are added to the prepared medium.
- Temperature ranging from 28-30oC, pH 2-4, and oxygen concentration are adjusted strictly to maximize the production of citric acid
- The agitation is constant during submerged fermentation as this ensures suitable mixing and oxygen distribution in the medium. This can be done using an aerated tank or a fermentor that possesses agitator capabilities.
Citric Acid Accumulation:
- The microbe metabolizes the substrate to convert sugars to citric acid. Certain strains of Aspergillus niger are genetically or chemically improved to increase efficiency.
- Citric acid is produced when the organism is in a particular phase. The production is carefully controlled to maximize the production.
Recovery and Purification:
- Calcium citrate is precipitated by the addition of lime to the fermentation broth. Further treatment with sulfuric acid liberates citric acid.
- Further solvent extraction and filtration get more refined the product.
- Purification is important since the final product should be devoid of impurities that might degrade the quality of its applications.
Crystallization and Packaging:
- Pure acid is crystallized, dried, and packed for industrial utilization.
- In the packaging, no contamination is allowed and the stability of the citric acid is ensured.
Applications of Citric Acid
Food and Beverages:
- It enhances the sour taste in sodas, candies, and jams.
- It serves as a preservative in processed foods. It prevents spoilage by inhibiting the growth of microorganisms on the products.
- Citric acid is greatly used in manufacturing soft drinks like cola, carbonated fruit drinks, and energy drinks for their sour flavor. It also maintains the pH levels in fruit-based jams and preserves.
Pharmaceutical Industry:
- Used in effervescent tablets and syrups for the sake of improving its taste and solubility .
It is used as a stabilizer for active ingredients in medicines.
- Citric acid is also used in intravenous fluids to act as a buffer that keeps the blood’s pH balance intact.
Industrial and Domestic Applications
- Citric acid acts as a descaling agent in the dishwasher and washing machines by eliminating lime scale.
- It serves as a chelating agent in cosmetics to balance pH and immobilize metal ions.
- It is applied as an ingredient in cleaning agents for dissolving calcium and magnesium, which are typical components of lime scale.
Biomedical Applications
- It serves a part in topical wound healing preparations and anticoagulant solutions.
- Citric acid is added to some blood anticoagulant formulations to prevent clotting during a procedure.
Citric Acid Cycle Products
Citric acid is a very important factor in the Krebs cycle, a metabolic pathway that utilizes carbohydrates, fats, and proteins to produce energy. Byproducts of this cycle include ATP and NADH, which can be used to fuel cellular functions. Similar principles have made industrial application based on the chelating and antioxidant properties of citric acid possible for stabilizing and enhancing products.
ATP and NADH play significant roles in biotechnology and industrial applications. ATP, a universal energy currency, is essential in biomanufacturing processes like fermentation and enzymatic synthesis, enabling energy-intensive reactions. It is also used in diagnostic assays to monitor cellular activity.
NADH, as an electron carrier, finds applications in biosensors for detecting metabolic activity and environmental pollutants. It is crucial in enzymatic reactions for producing fine chemicals, pharmaceuticals, and biofuels. NADH is also integral to research in metabolic engineering, supporting the optimization of microbial strains for efficient bio-production. Together, these molecules drive advancements in industrial biotechnology and sustainable manufacturing.
Common Citric Acid Substitutes
Although citric acid is very versatile, there are occasions when a replacement is needed. These are:
- Lemon Juice or Vinegar: Natural sources with near identical acidity, used in cooking.
- Tartaric Acid: Used in the manufacturing of baking powders and wine.
- Ascorbic Acid: Vitamin C-rich replacer for preservation and flavor.
Citric acid substitutes find particular usefulness among those who are sensitive or allergic to citric acid.
There are substitutes for citric acid that work well for specific applications-for example, in flavoring or preservation, and while they bring about the same level of acidity, they can also affect the taste or texture of the product. Generally, in baking, the two alternatives for recipes requiring acidity for leavening are tartaric acid and ascorbic acid.
Also Read: What are Artificial Flavors? Understanding the Ingredients and Uses
Sustainability and Innovations in Citric Acid Production
As environmental awareness increases, the citric acid industry is shifting to a sustainable future. An important area of focus is renewable substrates-from agricultural wastes like wheat bran and rice husks for the purpose of substituting non-renewable resources.
These endeavors are also intended to help maintain a circular economy wherein industrial waste is turned into more valuable products; hence, the negative impacts of citric acid production on the environment are reduced. Using renewable materials in production not only reduces waste but also the carbon footprint related to that traditional production; thus, citric acid would be softer on nature and kinder to the Earth.
Conclusion:
Citric acid manufacture has changed through time from natural extraction towards effective and eco-friendly microbial fermentation, initiated by Aspergillus niger. This has increased production efficiency in addition to reducing the environmental impact. Citric acid is required in all food industries, pharmaceuticals, and cleaning products, hence vital in everyday life.
For a business that looks for innovation or sustainability, Elchemy benefits from state-of-the-art technologies to optimize the production process. Being a part of sustainability, Elchemy allows for the simplification of operations while maintaining high quality. Contact us today to explore how we can help you in achieving your citric acid production goals.
