Citric Acid (C₆H₈O₇) 77-92-9

Citric Acid (C₆H₈O₇) is a weak organic tricarboxylic acid that occurs naturally in citrus fruits and is produced industrially through fermentation of carbohydrates by Aspergillus niger. It is a white crystalline powder with a molecular weight of 192.12 g/mol, highly soluble in water, and widely used as an acidulant, preservative, chelating agent, and pH regulator.

Anhydrous citric acid (C₆H₈O₇) contains no water of crystallization and has approximately 99.5-100% purity. Monohydrate citric acid (C₆H₈O₇·H₂O) contains one water molecule per citric acid molecule and has approximately 99.5% purity on a dry basis but contains about 8.6% water by weight. Anhydrous is preferred for moisture-sensitive formulations. Monohydrate is more commonly used in food and beverage applications and is slightly less expensive.

Citric acid is used in soft drinks, fruit juices, and energy drinks to provide tartness and sourness. In candies and confectionery, it adds a sharp fruity flavor. In jams, jellies, and preserves, it adjusts pH for proper gelling and acts as a preservative. In dairy products and processed foods, it functions as an emulsifier, antioxidant synergist, and pH regulator. It is the most widely used acidulant in the global food industry.

Citric acid is an effective and environmentally friendly cleaning agent. Its chelating properties bind calcium and magnesium ions, dissolving hard water scale and soap scum. It is used in descaling agents for coffee makers and kettles, bathroom cleaners, dishwasher rinse aids, and all-purpose household cleaners. As a biodegradable alternative to phosphates and strong mineral acids, it is increasingly popular in eco-friendly cleaning formulations.

Citric acid is used in industrial water treatment for pH control and scale prevention, in oil and gas operations for formation acidizing and iron control, in metal finishing for cleaning and passivation, in electroplating baths as a complexing agent, in textile processing for dye fixation, and in construction materials such as cement retarders and gypsum plaster additives. Its biodegradable nature and non-toxic profile make it an attractive alternative to mineral acids in many industrial processes.