It is taken up by the liquid so quickly that
the method used to prepare the beverage makes little difference as to
the amount obtained. In other words, tea made by pouring water through
the leaves will contain nearly as much of the stimulant as tea made by
boiling the leaves.
14. In addition to the stimulant, tea and coffee contain _tannin_, or
_tannic acid_, an acid that is also obtained from the bark of certain
trees and used in the tanning of animal hides in the preparation of
leather. Tannin is not taken so quickly from tea and coffee by the hot
liquid used in preparing the beverage as is the stimulant, so that the
longer tea leaves and coffee grounds remain in the liquid, the more
tannic acid will be drawn out. This fact can be detected by the bitter
flavor and the puckery feeling in the mouth after drinking tea that has
been allowed to remain on the leaves or coffee that has stood for some
time on the grounds. Tannic acid has a decidedly bad effect on the
digestion in the stomach, so that if improperly prepared tea or coffee
is indulged in habitually, it may cause stomach disorders.
TABLE I
STIMULANT AND TANNIC ACID PRESENT IN STIMULATING BEVERAGES
-------------------------------------------------------------
Quantity of Quantity of
Beverage Stimulant Stimulant Tannic Acid
Grains Grains
-------------------------------------------------------------
Coffee Caffeine 2 to 3 1 to 2
Tea Theine 1 to 2 1 to 4
Cocoa or chocolate Theobromine 1 to 1-1/2 1/2 to 1
-------------------------------------------------------------
15.
Pages:
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395