categorization of teas

Infused tealeaves clearly indicate the degree and manner of fermentation they have gone through. These are 1:1 photos taken on a light box. Note the differences in leaf sizes and characters. They are not only plucks from different growth stages, but also from different cultivars. (from left) Kaihua Longding (a green tea); Silver Needles (a lightly oxidized tea); White Cockscomb (a Wuyi oolong); Tanyang Gongfu (a black tea); and Puer Indigenous (a post-fermented tea).

categorization of tea according to the manner of fermentation

Tea has been categorized under various concepts, such as production location, grading, appearance, or flavouring, etc. I think the best universal concept so far bases on the degree and manner of “fermentation” that a tea undergoes during production. The commonly understood terms of “Black” and “Green” teas fit in this concept.

Fermentation in tea production refers specifically to the process when enzymes of the leaf oxidize the leaf’s other constitutional matters. An example is the oxidation of catechins in the green leaves to form theaflavin in black tea. There are over 300 compounds in the fresh tealeaves which can interact with one another during the bio activities in the production processes to form as many as 500 resultant matters that constitute the aroma, taste, texture, other gastronome and health effects of any final tea selection.

Tealeaves left in a pile a few hours after plucked. The material nature, i.e. chemical composition of the leaves inevitably undergoes much change if not atteneded to immediately after plucked.

The same compounds can form anti-quality matters too, when the conditions and processing are not optimum. Enzymes leak when the cellular structure of the leaf is broken or weakened. This can happen in an controlled environment during production, or it can happen when the plucked leaves are mis-handled, such as piled in a basket for a long time. Uncontrolled oxidation leads to poor quality. Controlling how the tea ‘ferment’ is one of the vital elements in determining the final quality. An excellent example is the category of oolongs — selections can be dramatically different in taste and aroma because the way the leaves are oxidized are different from one and other. However, there is also the key factor of horticulture.

Very often I come upon theories that all teas come from the same plant and it is only the degree of fermentation that gives each tea its character. The truth is very opposite of that. Sub-varieties, cultivars, in addition to the elements of growing environments, plucking condition and the quality of the production process itself are crucial factors that contribute to the gastronomic character of a tea. <read more about this>

There are also teas which forms and tastes are altered AFTER the fermentation process is done, most even after drying. One common example is the scenting of teas. Pleasant aromas, such as that directly from real flowers, or that from extracts or from artificial agents, are infused into the dried leaves of green, black or oolong teas. Some products further exploit the idea of exotic flavouring to add dried fruits or flowers. The form of tea can also be modified after the leaves are produced, such as by compressing, grounding or turning into extract granules. read on »