Method for crystallization of aromatic amino acids, enabling sustainable cycle of ammonia

A method for crystallization of an aromatic amino acid, comprising

• (a) mixing a reaction solution comprising aromatic amino acid crystals and ammonia to obtain a dissolved solution in which the aromatic amino acid crystals are dissolved;
• (b) crystallizing the obtained dissolved solution to obtain a concentrated solution comprising aromatic amino acid crystals;
• (c) recovering gas comprising ammonia, produced during the process of crystallizing;
• and
• (d) reusing ammonia derived from the recovered gas as ammonia of the step (a);
• wherein the step (b) and step (c) are conducted simultaneously or sequentially, and
• the step (a) to step (d) are performed repeatedly.