• Picking: Tea leaves and flushes, which includes a terminal bud and 2 young leaves, are plucked from Camellia sinensis bushes typically 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 labour 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 is also more difficult to harvest by machine on mountain slopes where tea is often grown.
   
• Withering/ Wilting: The tea leaves will begin to wilt soon after picking, with a gradual onset of enzymatic oxidation. Wilting is used to remove excess water from the leaves and allows a very slight amount of oxidation. The leaves can be either put under the sun or left in a cool breezy room to pull moisture out from the leaves. The leaves sometimes lose more than a quarter of their weight in water during wilting.
   
• 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.
   
• Oxidation / Fermentation: For teas that require oxidation, the leaves are left on their own in a climate-controlled room where they turn progressively darker. 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, although no true fermentation happens since this oxidative process is also not driven by microorganisms (in other steps of tea processing--aging for example--microorganisms might be used that actually do carry out fermentation). The tea producer may choose when the oxidation should be stopped, which depends on the desire qualities in the final tea as well as the weather conditions (heat and humidity. For light oolong teas this may be anywhere from 5-40% oxidation, in darker oolong teas 60-70%, and in black teas 100% oxidation.
   
• Fixation / Kill-green / Firing: Kill-green or shāqīng 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 some white teas and some black teas such as CTC blacks, kill-green is done simultaneously with drying.
   
• Sweltering / 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. The resulting leaves produce a beverage that has a distinctive yellowish-green hue.
   
• Rolling / Shaping: The damp tea leaves are then rolled to be formed into wrinkled strips, using a rolling machine which causes the tea to wrap around itself. This rolling action also causes some of the sap and juices inside the leaves to ooze out, which further enhances the taste of the tea. In many type of oolong, the rolled strips of tea leaf are then rolled to spheres or half spheres and is typically done by placing the damp leaves in large cloth bags, which are then kneaded by hand or machine in a specific manner. The strips of tea can then be formed into other shapes, such as being rolled into spirals, kneaded and rolled into pellets, or tied into balls, cones and other elaborate shapes.
   
• 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.
   
• Aging / Curing: While not always required, some teas required additional aging, secondary-fermentation, or baking to reach their drinking potential. For instance, a green tea pu-erh, prior to curing into a post-fermented tea, is often bitter and harsh in taste, but becomes sweet and mellow through fermentation by age or dampness. As well, oolong can benefit from aging if fired over charcoal. Flavored teas are manufactured in this stage by spraying the tea with aromas and flavors or by storing them with their flavorants.
  
   
  Classification of Tea based on Processing type:
  Tea is traditionally classified based on the techniques with which it is produced and processed which is based on the degree or period of “fermentation” the leaves have undergone:
  • White tea: Wilted and Unoxidized
  • Yellow tea: Unwilted and Unoxidized, but allowed to yellow
  • Green tea: Unwilted and Unoxidized
  • Oolong: Wilted, Bruised, and Partially Oxidized
  • Black tea: Wilted, sometimes Crushed, and Fully Oxidized
  • Post-fermented tea: Green tea that has been allowed to ferment/compost
   

Tea Processing Chart
[Click on chart to enlarge.]