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| Tsujimura (front row, second from left) is seen here with her students at Ochanomizu University in 1952. Tsujimura was passionate about training future scientists. |
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The leaves used in green tea, black tea, oolong tea,
and other varieties all come from one type of evergreen, a member of the
camellia family that grows in tropical and temperate regions. This consists
of a large-leaved species, Camellia sinensis var. assamica
(from Assam), and a small-leaved species, Camellia sinensis var.
sinensis (from China).
The green tea traditionally preferred in Japan--including sencha, gyokuro,
bancha, and hojicha--is made by steaming fresh leaves and using
heat to stop the oxidizing action of their enzymes. The leaves are not allowed
to ferment. Compared with teas in which oxidation and fermentation take
place, green tea preserves the original color of the leaves and has a certain
bitterness and astringency, but also a subtle sweetness. For black tea,
the leaves are fermented completely, and for oolong tea, heat is applied
midway through the fermentation process to stop it before it is complete.
The brown color of fermented tea leaves results from changes in the catechins.
Green tea is richer in catechins than other teas. Catechins belong to a
group of substances called polyphenols, which are thought to help remove
the "free radicals" that contribute to the aging of the body's cells and
can lead to such conditions as hardening of the arteries, blockage of the
blood vessels in the heart and brain, and cancer. For this reason, green
tea and the catechins it contains are now being eyed as possible keys to
preventing such ailments. |
