Citric acid is one of the most widely used food additives in the world, classified as E330. It is a natural organic acid found in citrus fruits, but commercially it is produced by microbial fermentation of sugars (primarily using Aspergillus niger). Citric acid performs multiple technological functions: acidity regulator, antioxidant, chelating agent, and preservative. Its dosage in food products is generally not restricted.
Applications
Citric acid is used across virtually every sector of the food industry — in confectionery (candy, jelly, marmalade), beverages (soft drinks, juices), dairy products, canned goods, sauces, and baked goods. It provides a clean, sharp sour taste, regulates pH to optimize the performance of gelling agents and preservatives, and acts as an antioxidant by chelating metal ions that catalyze oxidative degradation.
Physical and chemical properties
Chemical formula: C₆H₈O₇ (2-hydroxypropane-1,2,3-tricarboxylic acid). CAS number: 77-92-9. Appearance: white crystalline powder. Density: 1.542 kg/m³ (monohydrate), 1.665 (anhydrous). Melting point: 153 °C; decomposition: 176 °C. Water solubility increases sharply with temperature: 117 g/100 mL at 10 °C, 148 g at 20 °C, 383 g at 80 °C, and 548 g at 100 °C. It is also soluble in ethanol, acetone, and ethyl ether.
Safety considerations
Citric acid is classified as an irritant (Xi) under chemical safety codes. Risk phrases R36/37/38 indicate that it irritates eyes, respiratory system, and skin. Safety measures S26 and S37/39 require immediate eye washing with water upon contact and the use of eye and face protection when handling the pure substance. In food-grade concentrations, citric acid is considered safe for consumption and has no established ADI (acceptable daily intake) limit set by JECFA — meaning it can be used quantum satis (as much as needed for the technological purpose).
Find more information about food additives and acidity regulators in the articles below.