Determination of Conversion of Chlorophyll to Pheophytin in Green Tea

DOI Web Site 1 References

Bibliographic Information

Other Title
  • クロロフィルのフェオフィチンへの変化の測定法
  • Application of Dietrich's Method to Discoloration of Green Tea during Storage
  • Dietrich法の茶への応用

Search this article

Description

In order to study the discoloration of green tea during storage, we investigated the application of Dietrich's method, in which the conversion of chlorophyll to pheophytin was determined.<BR>The formula described by Dietrich was as follows:<BR>percent conversion= RX-R0/R100-R0×100<BR>where, R0: ratio of optical density (OD) readings 534 mμ/556 mμ for zero conversion<BR>R100: ratio of OD readings 534 mμ/556 mμ for 100% conversion<BR>RX: ratio of OD readings 534 mμ/556 mμ for the unknown<BR>Using green tea, the following equation was obtained.<BR>percent conversion= Rx-0.96/1.29 × 100<BR>Yet, as this equation may vary slightly with some conditions of analysis used, it seems to have need for each analyst to set up his own equation with each instrument.<BR>The procedure and calculation by this method in green tea are; add 40 ml. of 90% acetone to 0.3g. of powdered green tea in a 50ml. flask and extract pigments allowing to stand for 3 to 5 hours. Then, read the OD at 534 mμ and 556 mμ of the supernatant of the acetone extract and calculate percentage conversion by the above equation.<BR>Then, it was recognized that the percentage conversion in this method agreed approximately with that calculated from pigment contents which were estimated in the method of TAN et al.

Journal

References(1)*help

See more

Keywords

Details 詳細情報について

Report a problem

Back to top