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Journal of Tea Science ›› 2003, Vol. 23 ›› Issue (2): 99-104.doi: 10.13305/j.cnki.jts.2003.02.003

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Synthesis and Characterization of Highly Pure Theanine

YAN Shou He1, Jean-Pierre DUFOUR2, Marc MEURENS1   

  1. 1. Catholic University of Louvain, Department of Nutritional Biochemistry, Louvain-la-Neuve, Belgium;
    2. Otago University, Food Science Department, P.O. Box 56, Dunedin, New Zealand.
  • Online:2003-11-25 Published:2019-09-16

Abstract: An improved synthesis method of L-Theanine, γ - glutamylethylamide was reported as the dehydratation of L-glutamic acid to pyrrolidone carboxylic acid (PCA), then PCA reaction with absolute ethylamine (99%, gas-liquid) with the yield of 92.6%. After re-crystallization in 84% ethanol solution the highest pure theanine (A type) is obtained with a yield of 37.4%. The crystals appear as tetra-rectangular prisms with a silk luster under transmission and scanning electron microscopy (TEM and SEM). The melting point of A theanine is 224°C. The B theanine synthesized from L-PCA shapes as cabbage leaves with curved borders under SEM and with a m. p. of 217 - 218°C as reference data. By using HPLC, it is confirmed that A and B theanine are mix-isomers. The A theanine consists of 47.9% L-theanine and the B theanine consists of 90.9% L-theanine. The rotation (α) of 100% L- theanine was + 8.57°.

Key words: Theanine, Synthesis of theanine, Characterization of theanine

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