The Tea Detective
Uncovering and Exploring the Facts About Tea
Black Tea-Fully Oxidized
Black tea is the second most popular tea in the world.  Called Qi Hong or Red
Tea by the Chinese because of its coppery-red color, based on their system of
naming tea by the color or the liquid, rather than the leaf.

Black tea is the only one of the
six main types of tea that is
fully oxidized (sometimes erroneously termed
fermented).

The manufacturing methods and varieties of
black tea vary enormously from country to
country and sometimes even from region to
region within the same country.

But no matter the overall differences in manufac
turing from one country to another, there are al
ways four basic stages involved in the product-
ion of black tea:  withering, rolling, oxidation
(sometimes erroneously referred to as ferment-
ing or fermentation), and firing (drying).
There are two major types of processing methods for manufacturing black tea-orthodox and CTC
(cut-tear-curl).  Orthodox black teas are loose leaf artisan made teas in a variety of different
styles and types available from various countries around the world, including
China, India, Sri
Lanka, Kenya, and Indonesia, just to name a few.

                                       The CTC or cut-tear-curl manufacturing method is used in a number of
                                       countries, mainly for  producing tea bag
blends.

                                       The four basic stages of manufacture for orthodox teas begins with
                                       withering. This is meant to soften the leaves and reduce the moisture
                                       content inside, which starts out at between 78 to 80% after plucking.

                                       For this step the leaves are spread out in a thin layer in warm air for
                                       up to 18 hours, or until the moisture content has been reduced to
                                       about 55 to 70%.  The tea leaf is then soft and pliable and ready for
                                       the next stage, rolling.

The rolling step starts the oxidation process
by breaking the leaf's cells and releasing the
natural juices and chemicals.  This is done
with a rolling machine that presses and twists
the leaves, rupturing the inner cells.

After this first rolling, smaller pieces of leaf are
sifted out and larger pieces are placed back in
the rolling machine for a second, and some-
times even a third rolling.

 Sometimes the leaf is put through a rotor-
        vane machine that minces, twists, and
        breaks the leaf into even smaller pieces
        than the orthodox rolling machine, maxi-
        mizing production of the smaller pieces of
        leaf for broken grade tea.  (see our
naming and grading page for more on whole leaf and
        broken leaf teas).

        The third stage is oxidation.  It's during this stage that the leaf begins to develop the
        recognizable aroma and
flavor of black tea, darkening in color, and developing compounds
        called theaflavins and thearubigins, belonging to a group called polyphenols.

        These healthy antioxidants aren't as strong as the similar group of catechins including
        EGCG, found in
green tea, but they do provide considerable health benefits as well.

        For this third step the leaves are broken up following rolling, and spread out in thin layers
        in cool, humid air and left to oxidize for 20 to 30 minutes or more, depending on climate
        and air temperature.

        The fourth and final step is to stop the oxidation process and
        dry the leaf. For this step the leaf is placed in large, automatic
        dryers with a conveyor belt inside which carries it along, drying
        it as it moves.

        Another method of drying is to move the tea on a stream of
        hot air that is 240 to 250F (115 - 120C) reducing the moisture content of the leaf to just 2
        to 3%.  Called "fluid bed dryers," this method of blowing the particles of tea on a stream
        of hot air is the most efficient, ensuring that all the pieces of leaf are evenly dried.

           The CTC (cut-tear-curl) manufacturing method was developed in the 1950's in response to
        the ever growing popular- ity of the
tea bag.  With this process the leaf is withered the
        same as for orthodox tea, but rather than being rolled, a CTC machine is used to chop the
        tea into tiny pieces, with blades that rotate inside at various speeds.

        Another machine, called a Lawrie Tea Processor (LTP) is also used for this. similar to the
        CTC machine, the Lawrie Tea Processor rotating hammermill leaf disintegrator, tears and
        breaks the leaf into tiny particles.

        Oxidation, the third stage of processing CTC teas, and the fourth stage, drying, is the
        same as that for orthodox black teas.  
Enjoy.  
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