Tea Processing

Processed tea leaves need to be dried in order for them to be used. Drying heightens the flavors in the tea leaves as well. Let us take a look at the different drying methods:
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.
  • 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.
Less common drying methods:
  • Charcoal firing: where tea leaves are set in a shallow bamboo basket and heated slowly over hot coals.
  • Drying on heated floor: where tea leaves are dried on a thick masonry floor heated from below.
Drying For Shelf-Stability
Drying for stability means reducing the moisture level in the tea leaves to 2-3 percent. This makes the leaves shelf stable and slows oxidative processes within the leaves to a near halt. Tea makers then control the volume of air moving past the tea, the temperature of the air and the amount of time drying occurs to produce an agreeable tea.

However, they have to be careful during the drying process. Drying the tea too slowly will lead to stewing, which leaves a bitter taste in the tea, and drying it too fast results in the outside of the leaves drying much quicker than the inside, otherwise known as case hardening. In order for good quality tea to be processed, moisture loss has to be at roughly 2.8-3.6 percent per minute.

Drying For Flavor Enhancement
There are two optional processing methods known as finish-firing and roasting, both of which include heat. These two options are typically saved for the higher-end teas.

Finish-firing alludes to a very low temperature heating of tea leaves for several hours, usually in an oven or in shallow bamboo baskets over hot coals before being packed and shipped. Finish-firing enhances the flavor and scent of the leaves, but doesn’t necessarily change it.

While finish-firing doesn’t change the contents of the tea, roasting aims to do just that. It creates a toasty, much darker tea.