Tea Production

     All of the various types of tea produced worldwide
are basically derived from the same tea plant, Camellia
 sinensis
.  Different production techniques and processes
result in the variety of tea products on the world market.


     The tea leaf contains naturally-occurring acids that, 
whenexposed to oxygen, gradually darken the tea leaf’
scolor. 
The longer the exposure to oxygen, the darker
the leaf will become. The color change can be made
even more dramatic by crushing the tea leaf in order
to release the acids.
     The first and arguably most important step in tea production is the harvesting of the tea leaves. Only the newly sprouted top leaf of the tea plant is harvested for use in the production of the highest quality teas.  The selective use of the top leaf produces teas with a smoother taste and higher concentration of beneficial antioxidants. This selective harvesting requires hand picking, since no automated technique to date has been able to replace the human labor involved. 

       The subsequent steps in the production process vary depending on the type of tea desired, but ultimately end with drying the tea leaves in order to stop oxidation and ready the tea for sorting and packaging. If the tea leaves are dried immediately after cultivation,with no oxidation taking place, a pure green tea is produced. Approximately four to five kilograms of fresh tea leaves are required in order to produce one kilogram of dry tea.
 
        The fresh tea leaves are placed in withering troughs set on wire mesh.  Large fans blow air through the
leaves 
to reduce the moisture content.  The leaves must be spread by hand and all lumps or piles removed
so that maximum air flow reaches all the leaves and no heat is generated in the tea.
 Moisture content is
lowered by about 70%. 
After withering is completed, the leaves are passed through the sifting machine in
order to remove debris.
 
        From the withering racks, the soft green leaves pass to the rolling machinery where they are twisted and
rolled 
to break up the leaf cells and release the juices which give the tea its flavor. The first important chemical
change 
starts here when the juices, which remain on the leaves, are exposed to oxygen.
From the roller, the tea emerges as twisted lumps which are broken up by coarse mesh sieves or roll-breakers. 
The fine leaves fall through the sieves and are  taken to the fermenting rooms, while the coarse leaves are returned 
for further rolling.
        The oxidation that started in the rollers is completed in the fermenting room. Here, the tea leaves are spread
on cement or tile floors. It is this process of oxidation which distinguishes the black teas from green teas. During
this process, the substances contained in the leaf cell’s juices oxidize and cause the leaf to heat up. In this phase,
the 
green leaf gradually turns a copper color. In order to produce a high quality tea, the oxidation process must be
interrupted at its peak by passing the tea to the drying process.
        The purpose of drying the tea leaves is to stop further oxidation.  An automatic tea drier, consisting
of a large 
iron box, is used to dry the leaves evenly and thoroughly without burning them. Inside the drier,
the leaves travel 
slowly on trays from top to bottom while hot dry air flows around them. Careful regulation
of the temperature and 
the speed at which the trays move are the main determinants of a successful drying
process.