How is tea produced?
Leaves from the tea bush are generally harvested by hand, and as yet, there is no practical mechanical method of harvesting (it exists, but is only used in very low grade varieties due to the brutality of its operation on the leaves). Harvesting is therefore a time consuming process. After harvesting, tea is further processed by two methods, depending on the quality of the leaves:
Crush, Tear, Curl (CTC)
CTC is a method reserved for lower quality leaves, and is an inexpensive mechanical process which reduces the leaves to tiny little grains, similar in principle to turning wood into sawdust. The leaves are allowed to sit out for a short period of time until they wither, whereupon they are torn apart inside a machine that compresses the leaves, shreds them, and reduces them into tiny pieces. The leaves are then ‘fired,’ which means that heat is applied which dries them out. While this process would destroy the nuances of higher quality leaves, it has a number of advantages for lower quality leaves, which is why it is used. Not only is this a very inexpensive method of processing tea, but it can also allow a lower quality leaf to produce a more robust sup of tea as reducing the leaf to such a small size increases it’s surface area when exposed to hot water, allowing more flavor to escape into the brew. CTC tea is generally used in tea bags and when tea is used commercially, such as in making the base for bottled iced teas, for example.
Orthodox processing is a more time consuming, hand crafted methodology reserved for higher quality leaves. While the process is slightly different depending on the type of tea being processed (white, green, oolong, or black tea), the basic method follows a specific path: withering, rolling, oxidation (fermentation), and firing.
After being harvested, the leaves are spread out and allowed to wither, or lose moisture, usually out of direct sunlight. This allows the next step, rolling, do be done without overly damaging the leaves.
Next the leaves are rolled, often mechanically, and the slight pressure creates microscopic damage to the leaves’ cellular walls. This process initiates a complex series of chemical reactions, which allows a myriad flavors to be brought out of the leaves. The leaves are also broken up to varying degrees, depending on the quality of the leaf, and the desired use of the product.
- Oxidation (fermentation)
The next step is oxidation, by which oxygen reacts with the various chemicals in the leaves, darkening the leaf and further enhancing the flavor. Historically the term ‘fermenting’ was used to describe this process, and will still be found in some texts, however oxidation is a chemical reaction, and fermentation is the action of bacteria or yeast upon a polysaccharide (sugar), and not what occurs within the leaf. Thus, modern processors no longer use this term. The longer oxidation takes place, the darker the leaf will become, and the more intense the flavor will be. There is, however a careful balance that must be maintained, as longer oxidation will also cause a leaf to lose its complexity in favor of a stronger taste. Different styles of tea are allowed to oxidize for different periods of time. White and green teas are not oxidized at all. Oolongs are oxidized anywhere from 30% to up to 70%. Black teas are fully oxidized.
The last stage is when the leaves are ‘fired,’ or heated, in order to stop the ongoing chemical reactions (oxidation). This also dries out the leaves in preparation for proper storage.
There are exceptions to the rule, as there exist teas that are not withered, for example, merely fired and packed for storage. White teas are not rolled, either, as this would damage them, so careful steps are taken to ensure certain teas are protected from certain process, which also results in the distinction between the myriad of varieties available. These steps, however, describe the path that most teas take during processing.