| 摘要 |
PURPOSE:To produce L-tryptophan having improved color tone and high commercial value by adding an aliphatic lower alcohol to an aqueous solution of L- tryptophan having pH of 4-6 at a temperature between 60 deg.C and the refluxing temperature of the hydrated aliphatic lower alcohol. CONSTITUTION:L-tryptophan is crystallized from an aqueous solution of L- tryptophan having pH of 4-6 by adding an aliphatic lower alcohol to the solution at a temperature between 60 deg.C and the refluxing temperature of the hydrated aliphatic lower alcohol. The concentration of L-tryptophan before the addition of the aliphatic lower alcohol is 5-30wt.%, preferably 10-20wt.%. The amount of the aliphatic lower alcohol is selected to give an alcohol concentration of >=5wt.%. The crystallized L-tryptophan is recovered by filtration, washed with water or a hydrated aliphatic lower alcohol and dried in air or nitrogen atmosphere preferably at <=80 deg.C to obtain L-tryptophan having excellent color tone and containing little coloring component. |
