What is Citric Acid?

Citric Acid is a weak organic acid naturally found in citrus fruits—especially lemons and oranges—responsible for their sour taste.
Its chemical formula is C₆H₈O₇.
It is widely used as a food additive, cleaning agent, preservative, and nutritional/pharmaceutical supplement.

Other Names:

Citric Acid is also known as Lemon Acid, Sour Salt, Lemon Juice Crystals, or by its IUPAC name: 2-Hydroxypropane-1,2,3-tricarboxylic acid.

Types of Citric Acid Available:

• Anhydrous Citric Acid
• Monohydrate Citric Acid

Difference Between Anhydrous and Monohydrate Citric Acid:

The main difference lies in water content and crystallization method:

• Monohydrate Citric Acid: Contains one molecule of water (H₂O) per citric acid molecule. Produced by crystallization in warm water.
  Formula: C₆H₈O₇·H₂O
• Anhydrous Citric Acid: Contains no water molecules. Produced by crystallization in cold water.
  Formula: C₆H₈O₇

Applications of Citric Acid (Food & Industrial Grades):

Citric Acid is a natural flavoring agent, preservative, antioxidant, and pH regulator used across multiple industries.

1. Food Industry:

• Used as a flavor enhancer and preservative in beverages, soft drinks, candies, and ice creams.
• Acts as an emulsifier in some dairy products such as ice cream.
• Gives the distinct tangy flavor to many processed foods.

2. Cosmetics and Personal Care:

• Used as a pH adjuster and exfoliating agent in skincare and cosmetic formulations.
• Helps remove dead skin cells and brighten complexion.
• Present in products that reduce wrinkles, acne, and skin discoloration.
• Found in peeling masks, creams, and shampoos.

3. Pharmaceutical Applications:

• Used as a preservative for blood storage, a buffering agent, and an antioxidant in medicines.

4. Detergents, Cleaners, and Disinfectants:

• Acts as a chelating agent (binds metal ions) and water softener in detergents.
• Helps reduce hardness of water, improves foam, and enhances cleaning efficiency.
• Used in hand and body washes, household cleaners, and industrial cleaning products.

5. Water Treatment:

• Used to remove lime and scale deposits from boilers and evaporators.
• Acts as a natural chelating agent to break down trace metals in water.
• Ideal for softening hard water in an eco-friendly manner.

Comparison: Citric Acid vs. Ascorbic Acid

Production Methods of Citric Acid:

1. Extraction from Citrus Fruits (Traditional Method):

• Obtained from lemons, oranges, grapefruits, and sour oranges via pressing, filtration, and crystallization.
• Advantages: 100% natural, small-scale use.
• Disadvantages: Low yield, seasonal dependency, and high cost—not suitable for industrial production.

2. Microbial Fermentation (Modern Industrial Method):

• The most common industrial process today.
• Uses fungi such as Aspergillus niger to ferment sugar-based substrates (e.g., molasses, starch, corn, or agricultural waste).

Process Overview:

1. Substrate Preparation:
   • A sugar-rich medium (molasses, starch hydrolysate, etc.) is prepared and purified.
   • pH and nutrients (nitrogen, phosphorus, magnesium) are optimized.
2. Inoculum Preparation:
   • Aspergillus niger spores are cultured in small sterile media to create an active starter culture.
3. Fermentation:
   • Conducted in bioreactors under controlled conditions (28–30 °C, pH ≈ 2–3).
   • Requires aeration and agitation for oxygen supply.
   • Duration: 5–10 days.
4. Separation & Purification:
   • Biomass removed via filtration or centrifugation.
   • Citric acid is precipitated as calcium citrate by adding lime (Ca(OH)₂).
   • Then treated with sulfuric acid to release pure citric acid and form calcium sulfate (gypsum) as a byproduct.
   • The solution is filtered, decolorized, and crystallized into pure white citric acid crystals.

Fun Fact:
The fermentation pathway mirrors the Krebs Cycle (Citric Acid Cycle) — the same biological process used in cellular respiration!

Health Risks and Side Effects:

Although citric acid is Generally Recognized as Safe (GRAS), overuse or allergic sensitivity may cause:

• Allergic reactions (especially in those sensitive to molds like Aspergillus niger)
• Respiratory irritation or skin sensitivity
• Gastrointestinal issues if consumed excessively
• Enamel erosion and tooth decay
• Risk of kidney stones in predisposed individuals

Main Producers of Citric Acid:

• Iranian: Jovein
• Imported Brands: TTCI, Lemon, Insain

Factors Affecting Citric Acid Price:

1. Raw Material Costs: Sugar sources (molasses, corn, starch) and nutrients.
2. Production & Energy Costs: Electricity, water, and equipment maintenance.
3. Supply and Demand: Higher demand in food/beverage seasons raises prices.
4. Exchange Rate: Affects imported raw materials and product pricing.
5. Transportation and Logistics: Shipping and fuel costs.
6. Product Quality & Grade: Food and pharmaceutical grades are more expensive.
7. Geopolitical and Trade Factors: Sanctions, tariffs, and import policies.
8. Market Competition: More suppliers usually mean more competitive prices.

Domestic Production and Sales (Iranian Citric Acid):

Iranian Citric Acid is highly regarded for:

• High purity and long shelf life
• Low toxicity compared to other acidulants
• Wide use in food, beverages, cosmetics, adhesives, coatings, plastics, inks, and polymers
• Stable composition for up to five years in unopened containers

Where to Buy Citric Acid (Anhydrous & Monohydrate):

You can purchase high-quality Citric Acid from reputable chemical suppliers such as PetroAlton, offering competitive prices and bulk delivery options.

Fruits Rich in Citric Acid:

Citrus fruits such as lemons, oranges, and grapefruits contain the highest concentrations of citric acid, giving them their characteristic sour taste.

Is Citric Acid the Same as Vitamin C?

No — Vitamin C is Ascorbic Acid (C₆H₈O₆), a different compound with distinct biological functions.