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Journal of Tea Science ›› 2018, Vol. 38 ›› Issue (3): 244-252.doi: 10.13305/j.cnki.jts.2018.03.004

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Rapid Detection of Theanine in Green Tea Based on Direct-reading Colorimetric Strips

ZHU Chengbo1, WU Xiaomei1, FENG Lixia1, HUANG Xiangpeng1, PANG Linjiang1, YANG Huqing1, FANG Zhengwei1, WANG Ying1, LAI Shuyu1, ZHANG Yiming1,2,*   

  1. 1. School of Agriculture and Food Science, Zhejiang Agriculture and Forestry University, Hangzhou 311300, China;
    2. Innovation and Practice Base for Postdoctors, Yibin University, Yibin 644000, China
  • Received:2017-12-06 Revised:2018-03-05 Online:2018-06-15 Published:2019-08-28

Abstract: In this study, ninhydrin/titanium dioxide nanomaterials were constructed by using Sol-Gel method. These nanomaterial were then used as direct-reading colorimetric materials and printed on the surface loci of thin layer plate where theanine would migrate according to its retardation factor (Rf). In addition, ethanol: acetic acid developing system was chosen as developing reagent, the extraction solution of tea after being decolorized by ethyl acetate was analyzed by thin layer chromatography (TLC) via direct-reading colorimetric reaction. The results showed that the current direct-reading strip could effectively separate several amino acids in tea extraction under optimized conditions. The new constructed colorimetric nanomaterials had achieved a sensitive direct-reading coloration results for the target amino acid theanine, and the color spots on the strip were uniform and clear after self-coloration. Moreover, its color depth had a clear semi-quantitative relationship with its concentration. The current colorimetric strip has a serial of advantages including safety, easy-operation, convenient and low cost, and has a broad application prospect in fields such as quality identification of agricultural products and on-site rapid detection of amino acids.

Key words: green tea, theanine, direct-reading colorimetric strips, thin layer chromatography

CLC Number: