| 摘要 |
<p>A novel method for producing an organic acid which comprises subjecting an ammonium salt of an organic acid (A) such as a di-carboxylic acid, a tri-carboxylic acid or an amino acid to a reaction crystallization using an acid (B) satisfying the following formula (a), such as a mono-carboxylic acid, to thereby separate a free organic acid (A) as a solid: pKa(A) ≤ pKa(B) (1) wherein pKa(A) and pKa(B) represent pKa’s of the organic acid (A) and the acid (B), respectively, provided that, when an acid has plural values for pKa, pKa(A) or pKa(B) represents the smallest value. After the organic acid (A) is precipitated and separated, the resulting mother liquor is subjected to the separation of the acid (B) and then an ammonium salt of the acid (B), and is circulated for use to the reaction crystallization step. The ammonium salt of the acid (B) is decomposed into the acid (B) and ammonia, which are circulated for use, to the reaction crystallization step and as a neutralizing agent for a microbial conversion step, respectively. The method can be advantageously used for producing a free organic acid from an ammonium salt of an organic acid having a high melting point, in particular, an acid obtained through the microbial conversion of a carbon source in the presence of a neutralizing agent, with good efficiency at a low cost, while circulating for use a raw material used and by-products without disposal.</p> |
