Everyone talks about green tea. It’s good for you, it’s accessible. But do you know what makes a tea green? Of course you know that all tea comes from the same type of plant. That’s like saying that all wine comes from grape vines. What happens to the grapes determines the wine. It’s the same with tea. In China, green tea is plucked and then withered to reduce the moisture content and to make the leaf pliable for shaping. The leaves are then spread out in bamboo trays. (When plucked, a tea leaf has a moisture content of around 85%; after withering, it’s reduced to 25-50%.) . As the leaf loses moisture, the pressure on the cell wall diminishes. This pressure on the cell wall is called turgor and accounts for the rigidity of the plant. When turgor is lost, the plant wilts and is pliable. Think of a limp celery stalk verses a crisp one.
What distinguishes Chinese green tea is the chaoqing, which means “roasting out of the green.” This is a de-enzyming chemical process that improves flavor, takes any bitterness out and gives a clear infusion. Tossing the leaves in hot pans prevents any further oxidation and keeps the leaves green. Think of tossing string beans in hot oil.
Next comes shaping. Some teas are fired again and then shaped again. Shaping further breaks down the cell wall, freeing more enzymes. Certain teas are then shaped again, preventing further oxidation and taking out more moisture.
The final firing reduces moisture so that the leaves can be stored without threat of spoiling. Firing may be from charcoal or forced air or electric heaters. Finally, the tea is sorted.
Next time you sip green tea, think about the process. Later: different types of green tea from difference provinces of China. (Special thanks to the Specialty Tea Institute for this wealth of information.)