CITRIC-ACID PURIFICATION PROCESS USING COMPRESSED CARBON-DIOXIDE

Citric acid (CA) has successfully been separated from fermentation broth by a novel and unique purification process, which is characterized by organic solvent extraction and precipitation with compressed carbon dioxide (CO2) as a poor solvent. After the filtration of microorganisms, the condensed fermentation broth of CA was dissolved in acetone. In this extraction, a certain amount of impurities (mainly sugar) could be separated as precipitates. Compressed CO2 Was then dissolved in the acetone solution of crude CA to remove the residual impurities as precipitates using the anti-solvent effect Of CO2. The deposited impurities were readily separated from the acetone solution of CA by a settler. Finally, food additive grade CA was easily obtained by simple decolorization and crystallization methods. Also, CA crystals could be obtained by the anti-solvent crystallization with CO2.