Saving energy upon water removal in drying by making the α-polymorph of L-glutamic acid

ABSTRACT

Drying is an energy-intensive operation for the separation of a desired solid product, when it consumes 12–20% of the entire energy used in manufacturing processes. Without changing the existing drying method or equipment, making α-form of L-glutamic acid (α-Glu) by reactive crystallization can reduce the energy consumption for drying in terms of much less initial moisture content of 23.32% and time of 4.67 h , as compared to 48.52% and 6 h for its β-form in the present study. Upon drying, α-Glu shows less affinity for hydrogen bonding with water, as ammonia cations on α-carbon of L-Glu are projected on the α-Glu’s surface. On the contrary, more hydrophilic carboxylate anions on α-carbon are exposed on the surface of β-Glu, which tends to form agglomerates during reactive crystallization, causing stronger interaction with water. As a consequence, 35% of energy utilization in drying can be saved by making α-Glu.

KEYWORDS:

• Energy efficiency
• amino acids
• fermentation
• particle size
• powder handling

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Acknowledgements

This research was supported by the grants from the Ministry of Science and Technology of Taiwan R.O.C. (MOST 107-2221-E-008-037-MY3, 108-2218-E-008-013, 109-2811-E-008-516, and 110-2221-E-008-006-MY3).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

C. L. Yang and H. L. Lee contributed equally.

Additional information

Funding

This work was supported by the Ministry of Science and Technology, Taiwan [107-2221-E-008-037-MY3, 110-2221-E-008-006-MY3].