Microorganism Used
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
Applications
Used in food, pharmaceuticals, and beverages as an acidulant and preservative
