Tea processing is the method in which the leaves from the tea plant Camellia sinensis are transformed into the dried leaves for making tea.
Procedure
- Plucking: Tea leaves and flushes, which includes a terminal bud and two young leaves, are picked from Camellia sinensis bushes typically twice a year during early spring and early summer or late spring. . Picking is done by hand when a higher quality tea is needed, or where labour costs are not prohibitive. Tea flushes and leaves can also be picked by machine, though there will be more broken leaves and partial flushes reducing the quality of the tea.
- Withering / Wilting: . Withering is used to remove excess water from the leaves and allows a very slight amount of oxidation. it can be done outdoors, controlled withering usually takes places indoors. Freshly plucked leaves are laid out in a series of troughs and subjected to hot air forced from underneath the troughs.The process is also important in promoting the breakdown of leaf proteins into free amino acids and increases the availability of freed caffeine, both of which change the taste of the tea.
- Disruption: The leaves may be lightly bruised on their edges by shaking and tossing in a bamboo tray or tumbling in baskets. More extensive leaf disruption can be done by kneading, rolling, tearing, and crushing, usually by machinery.The bruising breaks down the structures inside and outside of the leaf cells and allows from the co-mingling of oxidative enzymes with various substrates, which allows for the beginning of oxidation.
- Oxidation / Fermentation: For teas that require oxidation, the leaves are left on their own in a climate-controlled room where they turn progressively darker. This is accompanied by agitation in some cases. In this process the chlorophyll in the leaves is enzymatically broken down, and its tannins are released or transformed. This process is sometimes referred to as "fermentation" in the tea industry.
- Fixation / Kill-green: Kill-green 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 and removing unwanted scents in the leaves, without damaging the flavour of the tea. Fixing is carried out via steaming, pan firing, baking or with the use of heated tumblers.
- Drying In order to keep the tea moisture-free, they are dried at various stages of production. Drying enhances a tea’s flavors and ensures its long shelf-life. Also, drying brings down the tea’s moisture content to less than 1%. To dry the leaves they are fired or roasted at a low temperature for a controlled period of time, typically inside an industrial scale oven. If the leaves are dried too quickly, the tea can turn abrasive and taste harsh.
- Aging
Some teas are subjected to aging and fermentation to make them more palatable. Some types of Chinese Pu-erh, for example, are aged and fermented for years, much like wine.
