The term "fermenting" is often used in the tea industry to refer to the processing of leaves, drying them so they can be later brewed. Tea is fermented by wilting the leaves, which are then exposed to the air and allowed to oxidize before being dried completely. There are three levels to which tea can be fermented: lightly fermented, semi-fermented and post-fermented. The most important thing is to use the freshest tea leaves possible. Treating the leaves carefully and allowing each step to be completed fully are also important parts of the process of fermenting tea.
Fresh leaves will offer the deepest and purest flavored tea. Tea leaves can be hand picked or machine harvested. Those who are involved with fermenting tea often say that it is always best to use hand picked tea leaves.
The fermenting process begins with an initial wilting of the fresh green leaves. Experts recommend that the tea leaves be wilted in the sun, which offers a natural, slow wilting process that cannot be achieved elsewhere. Sun wilting reduces the moisture content without entirely drying the leaves out. People who are making fermented tea should regularly check the leaves so their edges do not scorch or burn.
No matter the level of fermenting that the leaves will undergo, they should be treated very gently. After the leaves have been wilted, they must be stirred. This should be done with care so that the leaves are not damaged too badly.
When fermenting tea, the leaves need to rub against one another and to be be bruised in the process. Some methods of bruising the leaves call for tossing them together in a bamboo basket as opposed to stirring them with a spoon. Whatever method of bruising is chosen, tea leaves can be crushed, but they should not be torn in the process.
Bruising the leaves is a vital part of the process of fermenting tea. Through each bruised area, the enzymes of the tea leaf become filled with air. The more a leaf is bruised, the more the fermenting process is able to be successfully completed. The three levels of tea require different amounts of fermentation.
After the leaves have been been bruised, they need to be again exposed to the air. This is best done over a two to three day period. It is important that the leaves be kept in a dry place or else they can begin to rot or mold. Most techniques for fermenting tea leaves suggest that the leaves not be left outside during this part of the process as they need to be kept in a place where the temperature remains consistent.
Once the leaves have reached the peak of the process, it is time to stop the fermenting. To do this, tea leaves can be roasted or they can be placed in a tea leaf dryer. Once they have been fully dried, they should be stored in an airtight container so that they maintain their flavor.