What Is Citric Acid
Citric acid (CA) is an important organic weak acid with the molecular formula C₆H₈O₇. It is a white crystalline powders, colorless crystals or granules in appearance, odorless, easily soluble in water, and the solution is acidic. And it is slightly deliquescent in humid air. In biochemistry, it is an intermediate in the citric acid cycle (tricarboxylic acid cycle), which occurs in the metabolism of all aerobic organisms. Therefore, citric acid is mainly used as acidulant, flavoring agent, preservative and antistaling agent in food and beverage industry. It is also used as antioxidant, plasticizer and detergent in chemical, cosmetics and cleaning industries.
The product can exist in anhydrous or monohydrate form. Generally speaking, citric acid anhydrous crystallizes from hot water, while citric acid monohydrate crystallizes from cold water. Citric acid monohydrate can be converted into anhydrous citric acid by removing bound water at 78 °C. Citric acid is also soluble in absolute ethanol at 15 °C and can react with ethanol to form ethyl citrate. Once the temperature exceeds 175 °C, citric acid also decomposes and releases carbon dioxide.
| Item | Unit | Quality Standards | Analysis Results |
|---|---|---|---|
| Characters | --- | White or almost white, crystalline powder, colourless crystals or granules. Odorless, has a strongly acid taste. effloresces in dry air. Very soluble in water, freely soluble in ethanol. | Pass |
| Identification | --- | Pass Test | Pass |
| Appearance of solution | --- | Pass Test | Pass |
| Assay | % | 99.5~ 100.5 | 99.8 |
| Water | % | ≤0.5 | 0.15 |
| Readily Carbonisable Substances | --- | Pass Test | Pass |
| SulphatedAsh (Residue on Ignition) | % | ≤0.05 | 0.02 |
| Sulfate | mg/kg | ≤150 | <150 |
| Oxalate | mg/kg | ≤100 | <100 |
| Lead | mg/kg | ≤0.5 | <0.2 |
| Arsenic | mg/kg | ≤1.0 | <0. 1 |
| Mercury | mg/kg | ≤1.0 | <0.5 |
| Aluminium | mg/kg | ≤0.2 | <0.2 |
| Heavy Metals | mg/kg | ≤5.0 | <5.0 |
| Bacterial endotoxins | IU/mg | <0.5 | <0.5 |
| Conclusion：The product is in conformity with BP/USP/FCC/E330 | |||
Application of Citric Acid Powder in food industry
The monohydrate form is widely used as an acidulant in refreshing beverages, fruit juices, jams, fruit candies, and canned foods, and also serves as an antioxidant in edible oils. It enhances flavor and overall sensory quality, stimulates appetite, and supports the digestion and absorption of minerals such as calcium and phosphorus in the human body. While the anhydrous form is extensively applied in solid and instant beverage formulations due to its excellent stability and solubility. Its salt derivatives, including calcium citrate and ferric citrate, are commonly used as nutritional fortifiers to supplement calcium and iron in functional and fortified foods. In addition, ester derivatives such as triethyl citrate function as non-toxic plasticizers for food packaging films, and are also used as acidifying agents and preservatives in the food and beverage industries.
