1. Food Industry

Citric acid is one of the most widely used food acidulants in the world.

• Acidulant: Used in beverages, juices, candies, jams, canned foods, and baked goods to adjust taste and provide a refreshing flavor.

• Preservative: Lowers pH to inhibit microbial growth; often used together with potassium sorbate or sodium benzoate.

• Antioxidant synergist: Chelates metal ions to prevent oxidative rancidity of fats and oils.

• Effervescent agent: Reacts with sodium bicarbonate to generate carbon dioxide in instant drinks, effervescent tablets, and effervescent candies.

✅ Example: In carbonated beverages such as cola and Sprite, citric acid functions both as a flavor enhancer and preservative.

2. Pharmaceutical and Healthcare Applications

• Pharmaceutical excipient: Acts as an acidulant or buffering agent in drug formulations such as vitamin C effervescent tablets and oral liquids.

• Anticoagulant: Sodium citrate chelates calcium ions in blood and is used in transfusions and laboratory testing.

• Metabolic regulator: Participates in the tricarboxylic acid (TCA) cycle and assists in energy metabolism.

• Oral care: Used in dental cleaners to dissolve tartar and plaque.

3. Chemical and Personal Care Industries

• Metal cleaner: Effectively removes scale, rust, and oxide layers without damaging metal surfaces.

• Detergent additive: Chelates Ca²⁺ and Mg²⁺ ions in hard water to enhance cleaning efficiency.

• Cosmetics: Regulates pH, provides mild exfoliation, and stabilizes formulations; used in facial cleansers, toners, and shampoos.

• Electroplating and dyeing: Serves as a complexing agent, buffer, or neutralizer to improve coating quality and color brightness.

4. Agriculture and Environmental Applications

• Chelating agent: Forms soluble complexes with metal ions to enhance plant absorption of trace elements in fertilizers.

• Eco-friendly cleaner: Used to replace strong acids in cleaning boilers, cooling towers, and industrial equipment—non-toxic and biodegradable.

• Biodegradable acid: Serves as a biodegradable organic acid in wastewater treatment processes.

5. Other Specialized Applications

• Photography: Acts as a neutralizing agent in developer solutions.

• Plastics industry: Functions as a stabilizer or auxiliary plasticizer to improve PVC heat resistance and transparency.

• Paper and textile industries: Used to adjust pH and improve dyeing performance.

⚙️ Citric Acid Derivatives and Their Uses

• Sodium Citrate: Food buffer and medical anticoagulant.

• Calcium Citrate: Nutritional calcium supplement.

• Citrate Esters (e.g., Triethyl or Tributyl Citrate): Environmentally friendly plasticizers for flexible PVC and bioplastics.