Preparation of Partially Decaffeinated Instant Green Tea

Jian-Hui Ye, Yue-Rong Liang,* Jing Jin, Hue-Ling Liang, Ying-Ying Du, Jian-Liang Lu, Qian Ye, and Chen Lin
Zhejiang University Tea Research Institute, 268 Kaixuan Road, Hangzhou 310029, People's Republic of China
J. Agric. Food Chem., 2007, 55 (9), pp 3498–3502
DOI: 10.1021/jf070046c
Publication Date (Web): April 4, 2007
Copyright © 2007 American Chemical Society
*

 To whom correspondence should be addressed. Fax:  +86-571-86971704. E-mail:  yrliang@zju.edu.cn.

Abstract

The caffeine level of instant tea extracted from decaffeinated leaf tea with 4.0 mg g-1 caffeine is commonly above 10.0 mg g-1, the maximum limit of caffeine for decaffeinated instant tea. Further removal of caffeine by active carbon (AC) from the green tea extract was investigated. It showed that the removal of caffeine from the tea extract solutions depended on the treatment time and tea extract concentration while the ethanol concentration and pH had little effect on the removal of caffeine. According to the removal of caffeine and the ratio of total catechins to caffeine in the tested samples, the optimum decaffeination conditions were determined to be as follows:  tea extract concentration 15−30 g L-1 for common tea extract but higher for partially decaffeinated tea leaf extract; ratio of tea solution to AC, 100 mL:4 g; treatment time, 4 h; and natural tea extract pH. Instant tea powder extracted from partially decaffeinated leaf tea with a caffeine level of 4.03 mg g-1 and further decaffeinated by AC had a caffeine level of 7.81 mg g-1, which was 31% lower than that without AC treatment.

Keywords: Camellia sinensis; instant tea; caffeine; catechins; EGCg; HPLC; active carbon

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History

  • Published In Issue May 02, 2007
  • Received for review January 7, 2007. Revised manuscript received March 5, 2007. Accepted March 7, 2007. We thank the National Science Foundation of China for financial support of the present work (Project 30571192).

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