Citric acid CAS No. 77-92-9

Product Description

Citric acid is a weak organic acid, commonly found in citrus fruits such as lemons, limes, oranges, and grapefruits. It is a white crystalline powder with a sour taste, highly soluble in water, and has a pH of around 2.2 in a 1% solution. Citric acid is primarily produced industrially through fermentation using molds like Aspergillus niger, which is more cost-effective than extraction from fruits. It has a wide range of applications, including as a preservative, flavor enhancer, and pH regulator in the food and beverage industry; as a descaling agent and eco-friendly cleaner in household products; and as a pH adjuster and antioxidant in cosmetics. In the pharmaceutical industry, citric acid is used as an anticoagulant and in effervescent tablets. It is also used in industrial applications for water softening and boiler cleaning. Citric acid is generally recognized as safe (GRAS) by the FDA, but overconsumption may cause tooth enamel erosion or stomach irritation.

Product Use & Characteristics

Properties

• Chemical Formula: C₆H₈O₇
• Appearance: White crystalline powder or colorless transparent crystals
• Taste: Sour, similar to lemon juice
• Solubility: Highly soluble in water (59 g/100 mL at 25 °C)
• pH: Around 2.2 in a 1% solution
• Melting Point: ~153 °C (307 °F)
• Density: 1.665 g/cm³ (anhydrous)
• Acidity (pKa): 3.13, 4.76, 6.40 (for the three -COOH groups)
• Reactivity: Acts as a weak organic acid, chelates metal ions (e.g., Ca²⁺, Fe³⁺), and forms citrate salts (e.g., sodium citrate)

Characteristics

• Natural Occurrence: Found in high concentrations in citrus fruits like lemons, limes, oranges, and grapefruits. Also present in berries, pineapples, and tomatoes.
• Biological Role: Intermediate in the citric acid cycle (Krebs cycle) in cellular respiration.
• Antioxidant Properties: Acts as an antioxidant, protecting cells from damage.
• Chelating Agent: Binds to metal ions, enhancing mineral absorption and useful in various industrial applications.

Synthesis Methods

• Natural Sources: Extracted from citrus fruits and other fruits and vegetables.
• Industrial Production: Primarily produced through fermentation using molds like Aspergillus niger, which is more cost-effective than extraction from fruits.

Uses

• Food and Beverage Industry:
  • Flavoring Agent: Adds sourness to candies, sodas, and drinks.
  • Preservative: Extends shelf life by preventing bacterial growth.
  • Acidulant: Balances pH in jams, sauces, and canned foods.
  • Emulsifier: Helps keep oils and fats mixed in processed cheeses.
• Pharmaceuticals and Supplements:
  • Flavor Enhancer: Masks the bitter taste of some medications.
  • Preservative and Stabilizer: Extends the shelf life of drugs and supplements.
  • Mineral Absorption: Added to mineral supplements (e.g., calcium citrate, magnesium citrate) to enhance absorption.
  • Medical Applications: Used in creams for skin infections, to lower urine acidity, and to treat metabolic acidosis.
• Cleaning and Household Products:
  • Descaling Agent: Removes limescale from kettles, coffee makers, and dishwashers.
  • Eco-friendly Cleaner: Used in natural cleaning solutions.
  • Soap and Detergent Booster: Softens water and improves cleaning efficiency.
• Cosmetics and Personal Care:
  • pH Adjuster: Used in shampoos, lotions, and skincare products.
  • Antioxidant: Helps preserve creams and serums.
  • Exfoliant: As an alpha-hydroxy acid (AHA), it helps remove dead skin cells and improve skin tone.
• Industrial Applications:
  • Water Softening: Binds to metal ions (calcium, magnesium) in hard water.
  • Boiler and Metal Cleaning: Removes rust and mineral deposits.

Safety and Handling

• Hazards: Generally recognized as safe (GRAS) by the FDA, but concentrated forms can cause skin and eye irritation.
• Storage: Store in a cool, dry place; keep the container tightly closed.
• Potential Considerations: Excessive consumption may cause tooth enamel erosion or stomach irritation. Individuals with mold allergies may experience reactions to manufactured citric acid, as it is produced using Aspergillus niger.

Why us!

Qingdao Sigma Chemical Co., Ltd., established in January 2017 and headquartered in Qingdao, China, is a reliable chemical supplier. Specializing in pharmaceuticals, biochemical intermediates, and research chemicals, the company offers a diverse product portfolio, including peptides (e.g., Tirzepatide, Semaglutide), nootropics, veterinary products, and APIs, often marketed with ≥99% purity and COA certification. We provides R&D, custom synthesis, and contract manufacturing services at various scales, while claiming a global export presence across 100+ countries. With international warehouses in the USA, Europe, Australia, and Canada, Qingdao Sigma Chemical also facilitates drop-shipping and reshipments, positioning itself as a key supplier for laboratory and research applications.