アスパラギン酸の晶癖に及ぼす不純物の影響(<小特集>ハイオクリスタル)

抄録

The effects of impurities present in crystallizeds. solution on the change in the crystal habit of aspartic acid crystals were investigated. Aspartic acid is produced by an enzymatic method using fumaric acid as raw matcrials in an industrial scale. The characteristics of this method are to produce very limited amounts of sub-products such as other amino acids, compared with conventional fermentation methods. When aspartic acids were crystallized by a continuous crystallization at 50℃ with neutrallization by 98% sulfuric acid, the changes in the crystal habit from plate to pillar forms were observed with the operation times elapsed, maintaining the α form crystal structure.The plate form crystallized under the higher supersaturation in the vicinity of 5g/dl, irrespective of the existence of impurities. On the other hand, the impurities in the solution, mainly fumaric acid and malic acid, inhibited the growth rate along b-axis direction and the crystal habit changes to the pillar form crystals, when the supersaturation decreased as low as 2g/dl.