All true tea comes from the same plant, Camellia sinensis. The different varieties we enjoy are all due to how the tea leaf is processed. The following chart helps us to visualize the process, even though it is a simplified version of a plethora of variations. It was designed by Tony Gebely and shared with permission. https://www.worldoftea.org/tea-processing-chart/

PROCESSING TERMS

WITHERED: The moment a tea leaf is plucked from the tea plant, it begins to wilt naturally, a process called withering. This process is further controlled to reduce the moisture content and allow the development of  flavor and the aroma compounds of the leaves. Control is done outside with the leaves gently laid on bamboo mats or indoors with forced air. Withering is stopped when the correct amount of moisture has been extracted or the aroma of the leaves change. The longer the wither, the more aroma and flavor is achieved.

ROLLED/BRUISED: is done mechanically or by hand to damage the cell walls of the tea so that oxidation may occur. Maceration allows the most surface area to be exposed to oxygen. Rolling is also done with tumbling being the gentlest method of bruising.

OXIDIZED: refers to a series of chemical reactions that occur when the tea leaf is exposed to oxygen. This results in the leaves turning brown and the production of flavor and aroma compounds in finished teas. The more oxidation, the more flavor and aroma results. White and green teas have little oxidation while oolong (wulong) tea is a semi-oxidized tea and Black teas are almost fully oxidized.

FIXED:
There are various process that halt or prevent oxidation from occurring. This is called fixing. In tea, the leaves must be heated to approximately 150 degrees Fahrenheit to halt oxidation. Most common fixing methods:

• Pan Firing: where tea leaves are heated in a large metal pan or wok that is heated by gas or wood fire.
• Steaming: where steam is forced through the mass of tea leaves.
• Tumblers: where a heated tumbler is used to heat the leaves.
• Baking: where an oven type machine is used to heat the leaves.

Less common fixing methods:

• Sun drying: where the heat of the sun denatures the enzymes in the leaf by dehydration.
• Microwaving: where electromagnetic waves are used to quickly heat the leaves, seen more in commercial applications.
• Plunging in boiling water: where tea leaves are literally plunged into boiling water.

DRIED: This is done for shelf satiability or to enhance flavors. Most common drying methods:

• Commercial dryers: where perforated conveyors move the tea leaves through a heat source in an endless chain, or fluidized bed dryers where tea leaves are dried on a bed of hot air (see above photo).
• Oven drying: where tea is set on perforated trays in an oven and hot air is circulated through the tea via convection.
• Sun drying: where tea leaves are spread outdoors usually on shallow bamboo baskets to dry in the sun (see photo at top of post).

Less common drying methods:

• Charcoal firing: where tea leaves set in a shallow bamboo basket are heated slowly over hot coals.
• Drying on heated floor: where tea leaves are dried on a thick masonry floor heated from below.

FERMENTED: Fermentation in tea production refers to the breakdown of substances by bacteria, yeasts or other microorganisms.