等电点-冷却结晶去除谷氨酸中的焦谷氨酸

Removal of Pyroglutamic Acid from Glutamic Acid through Isoelectric Point Combined with Cooling Crystallization

研究搅拌转速、育晶时间、调酸速率、冷却温度4个因素对降低谷氨酸结晶中焦谷氨酸含量的影响。在保证谷氨酸回收率的基础上,确定焦谷氨酸含量达到欧盟E621标准(≤0.2%),其最优结晶组合为搅拌转速150r/min、育晶时间30min、调酸速率3drops/min、冷却温度5℃。在上述实验中,焦谷氨酸的初始含量均小于1%。通过延长育晶时间至60min,可使初始焦谷氨酸含量为1.27%的谷氨酸,在结晶后,焦谷氨酸含量降至0.18%。

The stirring speed, crystallization time, acid-adjusting rate and cooling temperature could affect the removal of pyroglutamic acid （PCA） from glutamic acid. The optimal crystallization of PCA to ensure that the content of PCA can meet the standard of European Union E621 was explored. The recovery rate of glutamic acid was high. The optimal crystallization conditions were determined as follows： stirring speed of 150 r/min, crystallization time of 30 min, acid-adjusting rate of 3 drops/min and temperature-cooling speed of 5 ℃. Under these conditions, the initial PCA content was below 1.0%. Through prolonging the crystallization time to 60 min, the final PCA content in glutamic acid could be reduced to 0.18% when the initial PCA content was 1.27%.