Abstract:

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%.

Key words: isoelectric point-cooling crystallization, glutamic acid, pyroglutamic acid, orthogonal array experiments