Microorganism Used in Production of Citric Acid:
- Aspergillus niger (fungus)
Fermentation Process:
- Fermenter Type: Stirred-tank or surface fermenters
- Fermentation Method: Submerged or surface fermentation
- Medium Composition:
- Carbon source: Molasses, sucrose, starch hydrolysate
- Nitrogen source: Ammonium salts, urea
- Metal ions (e.g., Fe²⁺) should be kept low to prevent byproduct formation
- Conditions:
- pH: 2.0-3.5 (acidic)
- Temperature: 28-32°C
- Aeration: High aeration for fungal growth
- Duration: 5-10 days
- Downstream Processing:
- Filtration to remove mycelium
- Precipitation with lime (Ca(OH)₂)
- Acidification with sulfuric acid to recover citric acid
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Applications:
- Used in food, pharmaceuticals, and beverages as an acidulant and preservative
