6l6 
THE TROPICAL AGRICULTURIST. 
[Feb. 1, 1902. 
Active Enzyme. Total Enzyme. 
A . ... 1-00 100 
B No. 1 ... 1-88 1-30 
B No. 2 .. 1-17 1'32 
B No. S ... 1-83 1-32 
la this case the active enEyme seems therefore to 
be a fair measure of the quality-producing char- 
acter of the leaf. The tame result is shown on 
garden C, as follows:— 
Active Enzyme. Total Enzyme. 
A 1-00 100 
CNo. 1 .. 217 2-18 
C No. 2 ... 1-44 1'68 
Here C No. 1 represents the very highest quality 
Assam bushes, and C No. 2, similarly, the beat 
China plants in the garden. In C No. 1, probably 
a little larger amount of stalk occurred, bat A and 
C No. 2 are absolutely comparable, and here it 
Vfill again be seen that flavour in the tea follows 
the enzyme in the leaf. Hence one may, I think, 
conclude that, other things being equal, the flavour 
in the product is materially connected with the 
quantity" of oxidase in the leaf from which is 
made. This conclusion, as stated above, will have 
to be supported by many more experiments before 
one can consider it satisfactorily established, but 
in the meantime there is strong and consistent 
evidence of its substantial accuracy. 
How then can this oxidase be increased in the 
leaf ? In a table on page 8, it was shown that, 
taking the various leaves on the same stalk, the 
amount of phosphoric acid varied very closely with 
the amount of oxidase. In addition to this I have, 
in a previous report,* brought forward very strong 
evidence that the "quality" of tea is materially 
influenced, at any rate in Assam, by the amount of 
phosphoric acid, and especially of available phos- 
phoric acid, in the soil. Now not only is phosphoric 
acid present in greater quantity in the leavs on the 
same stalk which give the most enzyme and pro- 
duce the best tea, but also there appears to be 
most of this constituent in the soil of those gardens 
giving leaf containing the most oxidase, and making 
the best tea. The following figures for the soil of 
the gardens A and 0, where the leaf mentioned 
above was obtained, show this very clearly. 
A C 
Percentage of Phosphoric Acid in Soil '061 '124 
The conclusion drawn in my previous report above 
mentioned, that in order to obtain high quality tea, 
there must in any case be a large quantity of 
phosphoric acid present in the soil, is here con- 
firmed, and this phosphoric acid becomes, in addi- 
tion, apparently connected with the quantify of 
enzyme in the tea leaf. 
INCHEASE OF FERMENT DUEING WITHEHING. 
One method by which the amount of oxidase 
present in the leaf maybe, and is normally, increased, 
inust not go by unnoticed. Withering has usually 
been considered to mean partial drying of the leaf 
at a low temperature so as to make it fit for roll- 
ing -and no more. My experiments showj however, 
that It has a fair more important function, which 
may explain to a certain extent the failure of ar- 
tificial methods by artificial heat to give a wither 
of the best kind. During this process, in fact, the 
amount of active ferment materially increases, in 
some cases by as much as 80 per cent, of its ori- 
ginal amount. Taking the leaf from gardens A and 
B above, the following increase took place 
during withering, due allowance having been made 
for the loss in water during the process, and taking 
tlie amount in the fresh leaf from Garden A as 
unity. 
* Tea Soils of Assam and Tea Manuring-Novem- 
AcTiTB Enzyme. Total Enzyme. 
In fresh In witliered In fresh In withered 
leaf. leaf. leaf. leaf. 
A ... 1-00 1-81 1-00 1-6!) 
B No, 1 1 88 2-48 I SO 1-87 
B No. 2 1 17 1 88 1-32 1-87 
B No. 3 183 2 19 1-32 219 
The increase in active ferment hence varies 
from 20 per cent- to 80 per cent, of the amount 
originally present, and this accounts very well for 
the fact that leaf rolled fresh without withering 
will never colour like properly withered leaf. 
CONCLUSIONS. 
What practical conclusions can therefore be drawn 
from the investigations which have just been de- 
scribed ? Will it be possible to prepare this enzyme, 
and at a time when the quality of the tea is inevi- 
tably low to add it to the fermenting leaf in order 
to improve the flavour ? This may be so, but is, to 
say the least of it, very doubtful. It must always 
be remembered in discussing the value of the presence 
of any ferment whatever, that it is not only the ferment 
whicli is of importance, but also the substances to 
be fermented. And in all vegetable products the 
growth of the material to be changed is coincident 
with that of the enzyme which is to change it. 
This is, for instance, the case in leaves or in seeds 
containing starch. So soon as starch apjiears, there 
also appears the diastase which is to - transform it 
into sugar. This is the same with other ferments and 
fermentable substances. It would therefore not seem 
likely at first sight that by merely adding the ferment 
alone from outside any great improvement would be 
efiected. But, so far, we are in ignorance what 
the substance is by which flavour is produced. The 
property may reside in the tannic acid, but this 
there is every reason to doubt, though of course 
to that constituent we do owe undoubtedly the 
purgency of the tea. It may be due to some changes 
in the resins, in the pectins, or in other products 
of the leaf of more or less obscure character. 
What these are and how they are changed will 
form the next step in this investigation. 
For the present it has been established — 
(1) . That the fermentation of tea is independent of 
living organisms, and is caused by an unorganised fer- 
ment or oxidase which can be extracted from fresh or 
withered leaf, 
(2) , That the quantity of this oxidase is greatest in 
the tip leaf of the shoot, and becomes less and less in 
the leaves as one descends from the growing point. It 
occurs in two forms, one more active than the other. 
(3) . That the oxidase acts best in a slightly acid 
juice, but excess of acid destroys its power, as well as 
any free alkali in the liquid ia which it works. 
(4) . That it is materially increased during wither- 
ing, and hence this process has a very important 
function in tea manufacture, independent of its 
necessity in making the leaf fit to roll. 
(5) . That, given leaf of the same character, the 
quality of the tea produced varies with the amount 
of oxidase, the larger the amount of oxiase the 
better being usually the quality of the tea 
(6) , That the amount of oxidase in the leaf is, 
in some way not yet known, dependent on the amount 
of phosphoric acid in the soil. 
The work liere detailed was done principally 
on the Moondakotee Tea Estate, Darjeeling, and 
to the manager, the agents, and the owners of 
that garden, I must here tender my heartiest 
thanks for help in every direction. To the 
Keporter on Economic Produces to the Govern- 
ment of India, ray thanks are also due for the 
use of his Calcutta laboratory in connection witli 
