RoLE OF OXYDASE IN THE PREPARATION OF TEA. 257 



tincture of guaiac and some hydrogen peroxide with great 

 intensity. 



In the following test, 6c c.c. of a cold prepared strong 

 alcoholic extract of the tea-leaves were diluted with four times 

 its own volume of water and separated into two portions. To one, 

 some of the purified enzyme solution above mentioned was added 

 in order to observe the action of the oxidase on the tannin of the 

 tea-leaves while the other portion served for control. Both 

 flasks were only half filled to admit air freely, and some ether 

 was added to prevent bacterial growth and plugged with cotton. 



The gradual change of color was very evident : 



Hence, an action of the oxidase of tea on its tannin is 

 evident, and there can be no further doubt, that the so-called 

 " fermentation " of the black tea leading to the formation of the 

 black color is due to the action of the oxidizing enzymes in the 

 tea-leaf. 



Finally also a test for catalase was made, not only with 

 fresh tea-leaves, but also with the residue after extracting leaves 

 at the ordinary temperature with alcohol and water, and its 

 presence recognised by the considerable development of oxygen 

 from dilute hydrogen peroxide solution. 



Some tests for oxidase and peroxidase were also made with 

 the green as well as the black tea of commerce, 2 but none of the 

 three enzymes mentioned was found. This is not surprising 

 since in the manufacture of black tea, the leaves are finally heated 

 up to ioo° C or even higher. In the green tea of commerce, it is 

 the steaming at the beginning of its preparation, that kills the 

 enzymes. 



Since Bertrand has observed a small percentage of manga- 

 nese in oxidizing enzymes and attributes to this metal an 

 essential role in their oxydizing actions, and since Lepinois 



Tannin solution 

 containing enzyme. 



Tannin solution 

 without enzyme. 



Green. 

 Yellowish green. 

 Brownish green. 



After 24 hours 

 .. 48 „ 

 „ 72 .. 



Somewhat brown 



Dark brown. 



Brown. 



1 This incomplete change of color is probably due to the acid reaction changing the 

 chlorophyll. 



* Prepared according to Japanese method. 



