Tea Processing Terms
Bruising: In order to promote and quicken oxidation, the leaves may be
bruised by tumbling in baskets or by being kneaded or rolled-over by heavy
wheels. This also releases some of the leaf juices, which may aid in oxidation
and change the taste profile of the tea.
Curling: While not always required, some teas required additional aging,
secondary-fermentation, or baking to reach their drinking potential. As well,
flavored teas are manufactured by spraying with aromas and flavors or by storing
them with their flavorants.
CTC. (Cut, Tear, Curl):
CTC processing method produces smaller leaf particles that give a stronger,
quicker brew. This method provides quick
processing for a high volume of tea leaves, as is commonly used in tea bags.
Drying: Drying is done to "finish" the tea for sale. This can be done in a
myriad of ways including panning, sunning, air drying, or baking. However,
baking is usually the most common. Great care must be taken to not over-cook the
leaves.
Firing: The
oxidized tea leaves are fired, or dried, by slowly heating them in a drying
chamber. This stops the oxidation process and dehydrates the leaves in
preparation for storage.
Fermentation/Oxidation: Oxidation begins during the rolling process as the
enzymes and juices of the broken leaves are exposed to air, resulting in a
natural chemical process that produces the unique aroma and flavor of the
tea. The rolled leaves are spread out in a temperature- and
humidity-controlled room where the tea leaf color deepens from green to a
reddish-brown, and then to
where they turn progressively darker. In this process the chlorophyll in the
leaves is enzymatically broken down, and its tannins are released or
transformed. Tea producer may choose when the oxidation
should be stopped. For light oolong teas this may be anywhere from 5-40%
oxidation, in darker oolong teas 60-70%, and in black teas 100% oxidation.
Kill-green: Kill-green or shāqīng (殺青)
is done to stop the tea leaf oxidation at a desired level. This process is
accomplished by moderately heating tea leaves, thus deactivating their oxidative
enzymes, without destroying the flavour of the tea. Traditionally, the tea
leaves are panned in a wok or steamed, but with advancements in technology,
kill-green is sometimes done by baking or "panning" in a rolling drum. In CTC
black teas, kill-green is done simultaneously with drying.
Picking: Tea leaves and flushes, which includes a terminal bud and 2 young
leaves, are plucked from Camellia sinensis bushes twice a year during early
spring and early summer or late spring. Autumn or winter pickings of tea flushes
are much less common, though they occur when climate permits. Picking is done by
hand when a higher quality tea is needed, or where labor costs are not
prohibitive. Hand-picking is done by pulling the flush with a snap of the wrist
and does not involve twisting or pinching the flush, since doing the latter
reduces the quality of the leaves. Tea flushes and leaves can also be picked by
machine, though there will be more broken leaves and partial flushes. It also
more difficult to harvest by machine on mountain slopes where tea is often
grown.
Rolling: Machines
break the cells in the withered leaves, which releases the tea leaf's juices
and enzymes. This exposes them to the air and enhances oxidation, which is
the next step. In the highest quality tea, this process is done by hand.
Shaping: The damp tea leaves are then rolled to be formed into wrinkle
strips. This is typically done by placing the damp leaves in large cloth bags,
which are then kneaded by hand or machine to form the strips. This rolling
action also causes some of the sap and juices inside the leaves to ooze out,
which further enchances the taste of the tea. The strips of tea can then be
formed into other shapes, such as being rolled into spirals, kneded and rolled
into pellets, or tied into balls and other elaborate shapes.
Wiltering: The freshly harvested tea leaves will begin to wilter soon after
picking, with a gradual onset of enzymatic oxidation. Wilting is used to remove
excess water from the leaves and allows a very light amount of oxidation. The
leaves can be either spread out onto trays under the sun or left in a cool
breezy room to pull moisture out from the leaves.
This preserves the leaf by removing most of the
moisture. As moisture evaporates from the leaf, it becomes soft and limp in
preparation for the next step, rolling.
Yellowing: Unique to yellow teas, warm and damp tea leaves from after
kill-green are allowed to be lightly heated in a closed container, which causes
the previously green leaves to yellow.
|
