This is an overview of the production of green tea, specifics may vary across each type of green tea but by and large the process is can be summed as the following main stages:
‘Shaqing’- which is translated literally from Chinese as ‘killing of the green’ is a crucial step in the production of green tea as it stops the oxidization of the tea leaves, preserving the characteristics of green tea including its appearance, aroma and taste. ‘Shaqing’ also dispels part of the grass smell and develops the aroma of green tea. Lastly, through the partial evaporation of moisture in green tea, the leaves are more pliable and easier to roll.
This process involves quickly heating the tea leaves to about 75°C-80°C (167°F-176°F) which destroys the active enzymes.
This is done either manually where the tea master heats the tea leaves with a wok while stirring and manipulating the tea leaves by hand or through a ‘shaqing’ machine which uses steam to produce the required heat.
Usually ~30%-40% of the moisture of the leaves is lost through the process of ‘shaqing’.
Rolling of the tea leaves is a common step in the production of most categories of tea. It helps the tea leaves take on the shape that we see the ‘final’ dry leaves be it twisted, curled into beads or flattened.
It is not mere aesthetics though- rolling also destroys the cell structure of the tea leaves and extracts the juices of the raw leaves which help in releasing the flavor of the tea when infused as well as improving the number of times the tea can be steeped. Also the rolled leaves are smaller in volume and hence can be packed or stored more efficiently.
Rolling of green tea can either be done hot or cold. ‘Hot rolling’ is rolling of the tea leaves when it is still hot from the ‘shaqing’ process. The heat causes the leaves to be more pliable and easier to be rolled or twisted to its desired shape.
For more tender leaves, the leaves are left to settle until the leaves cool significantly. As tender leaves contain less cellulose and hence are more pliable in nature, they can be rolled when they are cool. This better preserves the chlorophyll of the leaves and hence the natural green color of the leaves.
Rolling can be done by hand on a wok but apart from some of the most expensive green teas in China such as West Lake Dragon Well, it is largely mechanized. Some small farms have semi-automatic machines which are operated by hand but in larger factories, there are huge machineries to accomplish this process.
In general, the standard for higher grade green tea is that above 80% of the leaves must be twisted successful while the floor is 60% for lower grades
Drying is the final stage of the production of green tea and there are 4 main ways of doing so, namely steaming, baking, roasting and sun-drying.
This process sets out to improve the taste and nature of the tea leaves as well as reducing the moisture further to prevent ‘molding’ and prolong the shelf life of the tea.
Steaming is one of the oldest methods of producing green tea which has spread to Japan during the Tang Dynasty where the fundamental principles unchanged in the production of matcha today.
Steaming though usually does not produce the same full flavor as roasting and often the grassy smell is more prevalent and the tea itself is more astringent. As a result, steaming has largely been abandoned since the Ming Dynasty.
However ever since 1972, China has imported modern steaming machines from Japan and this method has made a comeback, predominantly for exports such as China produced Sencha.
Among the higher grades of green teas produced using steaming include Enshi Yulu from Hubei and Yangixan tea from Jiangsu.
Another method of drying green tea leaves involves baking. The leaves are placed into a ‘baking cage’ and baked until it is dry.
This method is also used for processing of scented tea such as jasmine tea.
Some famous varietals that are processed with this method include Huangshan Furry Peak, Taiping Houkui and Huading Yunwu.
Green tea leaves can also be dried by roasting or ‘frying’ them on a wok. This can be used for a varieties of teas including pearls and higher grade varietals like the famous Dragon Well, Bilochun and Liu An Gua Pian.
The final method is quite straight forward, is to arrange the tea leaves under the sun and let nature do its work.
This is common in Yunnan, Sichuan and Guangxi and generally is not used for higher grade green tea.
This is just a general guide on how green tea is processed as specifics differ across varietals and even among producers for the same type of tea.