The
process for making black tea is said to have been learned from that
for making oolong tea, or rather is an extension of it. The
traditional method of processing black tea involves dour basic
steps: withering, rolling (for gongfu only), fermenting, and drying
(firing, de-enzymizing).
First the leaves are spread out in the open for several hours on
bamboo trays - in the shade for the finer grades - to be wilted
until they are limp enough to be rolled without cracking. When they
reach this point they give out a fruity, apple-like fragrance.
The
nest step is rolling, sometimes preceded by repeated tossing of the
leaves in baskets. Rolling used to be done by hand between the palms
or against bamboo trays, with a worker going over the tray as many
as three to four hundred times. The purpose is to bruise the leaves,
breaking down their membranes to bring together the chemical
substances called catechins and the enzyme polyphenolase (polyphenol
oxidase) which activates the oxidation of the former. After rolling,
the lumps of leaves must be separated by a roll breaker.
Rolling the leaves gives them their future form. The two main
characteristics of a cup of black tea are its flavor, accompanied by
color, and the particular effect of the polyphenols, called pungency
or astringency. A twisted leaf releases less pungency and more
flavor during infusion, and does it over a longer time, thus
achieving a more even balance between the two.
Fermentation or oxidation goes on for several hours while the leaves
are spread out in a cool place. The leaves absorb oxygen which
activates enzymes to create essential oils and causes chemical
changes, oxidizing some of the polyphenols, or what is known as the
tannin. Leaves oxidized longer produce tea with more color but less
flavor. During the process, leaves begin to turn red around the
edges and to gives off a fragrance like almonds.
Firing, almost like stir-frying, is traditionally carried out in a
large metal work over a very hot fire. It stops the enzyme action,
sterilizes the leaves, and stops the fermentation process. Now this
step can be done in large ovens with temperatures up to 194 oF
(90 oC). Often the thicker, high-quality leaves alternate
several times between the fermentation and firing process.
Then the leaves, now 80% dry, complete their drying over charcoal or
wood fires. The last step is to sift the leaves to sort by size. It
is important that the size be uniform in each grade. Otherwise, as
smaller pieces infuse more quickly, uniform strength for each grade
could not be guaranteed. There are two main categories: the leaf
grade, (gongfu) and the broken grade used in teabags. The latter
produces a dark, strong brew more quickly. Fannings, one of its
subdivisions, is widely used in tea bags. A still finer sorting too
small for tea bags is called "dust" and used in tea bricks and
tablets.
The
process of black tea manufacture may seem finished, but there is one
more steep - blending to ensure a brand of consistent quality. This
is done by the big tea packers such as Lipton. Most name brand black
teas are blends and may include as many as twenty or thirty teas
from two or three countries.
Keemun is the best known of China's black teas. China exports 90% of
her black tea production, for green and oolong are preferred inside
China.
