Potentiometric flow-injection estimation of tea fermentation degree

SENSORS AND ACTUATORS B-CHEMICAL

卷:136

Article; Proceedings Paper

Nieh, Chi-Hua¹  Hsieh, Bo-Chuan¹  Chen, Po-Chung¹  Hsiao, Hsien-Yi¹  Cheng, Tzong-Jih¹  Chen, Richie L. C.¹ 

[1] Natl Taiwan Univ, Coll Bioresources & Agr, Dept Bioind Mechatron Engn, Taipei 106, Taiwan

关键词: Potentiometric;    Flow-injection;    Tea fermentation degree;    Redox potential;    Tea catechins;   

DOI  :  10.1016/j.snb.2008.09.024

来源: Elsevier

【 摘 要 】

A potentiometric flow-injection (FI) system was developed for estimating tea fermentation degrees; the method is based on the redox potentials or tea infusions. The infusions were extracted with phosphate buffer (10 mM, pH7.0), and injected (200 mu L) into the FI system (1 mLmin(-1)). The redox potentials (vs. Ag/AgCl) of carrier stream were monitored with a home-made electrochemical flow cell equipped with a platinum indicating electrode. Flow-injection strategy Successfully decreased the problem of electrode fouling with increased reproducibility (S.D.<1.5 mV) and elevated sample throughput (>20determination h(-1)). During indoor withering process (0-24 h) for making pouching tea, the redox potential of tea infusions rose (110-130mV) along with the depletion of tea catechins (100-75 mg g(-1) city tea powder, by HPLC). The system can also be used to estimate the fermentation degrees of commercial tea samples. For commercialization, the platinum electrode can be replaced with a screen-printed carbon-paste disposable electrode with similar performance. (C) 2008 Elsevier B.V. All rights reserved.

【 授权许可】

Free