Anhydrous citric acid is the dry form of citric acid. It contains no water in its crystal structure, which makes it easier to store, easier to handle, and more accurate to dose by weight. When people ask what is anhydrous citric acid, the simple answer is that it is citric acid without water of crystallisation. This difference is important in products where moisture control, shelf life, and consistency matter.
This blog explains what anhydrous citric acid is, its main properties, where it is used, how to handle it safely, and what to check when buying it.
Introduction
Citric acid naturally occurs in fruits like lemons and oranges, where it is always mixed with water. In industrial use, citric acid is often required as a solid ingredient that stays dry, free-flowing, and stable during storage and processing. Anhydrous citric acid, unlike the monohydrate form, contains no bound water, which helps reduce clumping and makes formulation calculations simpler.
What Is Anhydrous Citric Acid?
To clearly answer what is anhydrous citric acid, it is the water-free crystalline form of citric acid. Citric acid itself is a weak organic acid that is widely used as an acidulant, pH adjuster, and chelating agent.
Both anhydrous and monohydrate citric acid are the same chemical substance. The difference is physical, not chemical. The monohydrate form contains one molecule of water in its crystal structure, while anhydrous citric acid contains no water at all.
The chemical formula of citric acid is C₆H₈O₇. The anhydrous form has a molecular weight of about 192.12 g/mol. The monohydrate form weighs more because of the added water. In practice, this means anhydrous citric acid provides slightly more active citric acid per kilogram and behaves differently during drying, blending, and storage.
Key Characteristics
1.Chemical makeup
Citric acid has three acidic groups and one hydroxyl group. When dissolved in water, it releases hydrogen ions in steps, which gives it strong acidity and good buffering ability over a pH range of roughly 2 to 6.
Commercial anhydrous citric acid is usually made by fermenting sugars using Aspergillus niger. After fermentation, the citric acid is purified, crystallised, and dried to remove water.
It is sold in different grades:
- Food grade, used in foods and drinks
- Pharmaceutical grade, used in medicines and supplements
- Industrial grade, used in cleaning and technical applications
Food and pharmaceutical grades are typically at least 99.5 percent pure and have strict limits on impurities.
2.Appearance
Anhydrous citric acid is a white or colourless crystalline solid. It has no smell and a strong, sour taste. It is available as fine powder, granules, or crystals, depending on how it will be used. Particle size is chosen based on handling, flow, and dissolution needs.
3.Solubility
Anhydrous citric acid dissolves very easily in water, especially at higher temperatures. This makes it suitable for beverages, syrups, cleaning solutions, and pharmaceutical liquids. It also dissolves in alcohol to some extent, which is useful in some cosmetic and medicinal products.
4.pH and acidity
Citric acid is a weak acid, but because it has three acidic groups, it can lower pH effectively. In solutions, it:
- Reduces pH
- Helps limit microbial growth
- Forms buffer systems when combined with citrate salts
Citric acid solutions are acidic and are not alkaline or basic.
5.Stability and storage
Anhydrous citric acid is generally stable but can absorb moisture from the air. If exposed to humidity, it may form lumps or lose its free-flowing nature.
To maintain quality, it should be stored in sealed containers in cool, dry, well-ventilated areas. When stored correctly, anhydrous citric acid usually has a shelf life of two to three years.
6.Heating behaviour
When heated gently, anhydrous citric acid may lose surface moisture. At higher temperatures, it breaks down instead of melting cleanly. Excessive heat during processing can reduce quality, so temperature control is important.
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Common Uses by Industry
1.Food and beverage
In food and drinks, anhydrous citric acid is used to:
- Add a sour taste and balance flavours
- Lower pH to help preserve products
- Bind metal ions that can cause spoilage
It is especially useful in dry products like powdered drinks, seasoning mixes, and bakery premixes.
2.Pharmaceuticals and nutraceuticals
In pharmaceutical applications, anhydrous citric acid is used in:
- Buffer systems for liquids and injectables
- Effervescent tablets and powders
- pH adjustment to improve drug stability
The dry form helps reduce moisture in solid dosage forms.
3.Cosmetics and personal care
In personal care products, anhydrous citric acid is used to adjust pH in shampoos, cleansers, and skin-care products. It is also used in dry cosmetic blends and powdered masks because it dissolves easily during mixing.
4.Cleaning and industrial use
Citric acid is widely used in cleaning products to remove limescale and mineral deposits. Anhydrous citric acid is common in powdered descalers, dishwasher formulations, and industrial cleaners where moisture control is important.
5.Other applications
Other uses include laboratory work, metal cleaning, electroplating baths, and home DIY products such as bath bombs and cleaning powders.
5. Handling and Safety
1.Safety overview
Anhydrous citric acid has low toxicity but can irritate the eyes, skin, or respiratory system if dust is inhaled or if contact is prolonged.
2.Safe handling practices
Good handling practices include:
- Wearing gloves and safety glasses
- Using dust masks in dusty environments
- Ensuring good ventilation
- Washing hands after handling
3.Storage and transport
Store anhydrous citric acid in sealed containers away from moisture, strong bases, and oxidising agents. It is generally not classified as hazardous for transport but must be properly packaged.
4.Disposal
Small amounts can often be diluted and disposed of according to local regulations. Larger quantities should follow site-specific waste management procedures.
Buying Guide
When buying anhydrous citric acid, check:
- Grade and purity
- Moisture content and loss on drying
- Particle size
- Certifications such as FCC, USP, or Ph. Eur.
- Availability of COA, SDS, and traceability documents
Packaging options range from small bags to bulk containers, depending on usage volume.
Conclusion
Anhydrous citric acid is the dry, water-free form of citric acid used across food, pharmaceutical, cosmetic, and cleaning applications. Its strong acidity, buffering capacity, and metal-binding properties, combined with low moisture content, make it a reliable ingredient for many formulations and help support stable products and efficient processing.
In simple terms, anhydrous citric acid is citric acid without water of crystallisation. This often improves flow, enables more accurate dosing, and supports moisture-sensitive formats such as dry blends, powders, tablets, and effervescent products.
At Scimplify, anhydrous citric acid is supplied as a high purity, dry crystalline material with controlled moisture and consistent performance, supported by COA and TDS documentation. It is packed in 25 kg HDPE lined paper bags, stored best in cool and dry conditions, and typically carries a shelf life of 3 years. The product is free from major allergens, produced via fermentation, and suitable for vegan, halal, and kosher requirements. USP and IP grades meet pharmacopeial purity standards and are widely used across dietary supplements and functional food applications.
