Earlier on this blog we posted these articles: Getting to Know Your Tea Terms: Oxidation and Getting to Know Your Tea Terms: Fermentation. Now it’s time to explore a questionable tea term: post-fermentation (or alternately “post-fermented”). The first thing that probably jumps to your mind is pu-erh tea, but there’s more to it than that!
|Pu-erh is the biggest group of these so-called
“post-fermented” teas. This 2009 Menghai 7562 Classic
Ripe Pu-erh Brick tea has had the fermentation
process speeded up using the Do Wui process.
In review, oxidation is the loss of electrons during a reaction by a molecule, atom or ion; for tea this means that the leaves take in oxygen, igniting a chemical reaction that converts tea catechins into theaflavins and thearubigins and thus changing the leaves from green to shades of brown, depending on the amount of oxidation. In contrast, fermentation means that tea leaves are exposed to microflora, humidity, and oxygen in the air which may also produce some reactivated oxidative enzymes in the leaves. This process alters the aroma and flavor of the teas, mellowing them, and turning them from being astringent or bitter into ones with pleasant mouthfeels and aftertastes. Yes, oxygen is involved here but in conjunction with other factors.
So, on to post-fermented teas.
What Is Post-Fermented Tea?
This is a term used by many tea folks, even those who have been dealing with tea on a professional basis for many years, who are using “fermentation” instead of “oxidation.” The term “post-fermented” is supposed to indicate a tea that undergoes further processing after the normal steps are done: withering, oxidizing (which they call “fermenting” out of a sense of tradition instead of clarity), fixing, shaping, sorting, drying. Some sites, including Wikipedia, have switched already from using “post-fermented” to using “fermented” and sticking with “oxidized” for the processing step after withering. Okay, from here on we’re calling these teas “fermented” (also known as “aging the tea”). It’s more accurate and simpler. Oxidation is not fermentation. And these teas are not undergoing additional processing after the true fermentation process. So “post-“ is not needed.
A properly fermented tea has been stored under the proper conditions (right humidity level, clean, good air flow, etc.) and has thus matured in a consistent manner without fear of mold developing. It infuses a darker transparent liquid with wonderful aroma, a flavor with little or no bitterness and astringency, and a texture that ranges from silky to velvety. Repeated infusions will be increasingly better.
Some Fermented Teas:
Pu-erh teas (aka Puer, Puerh, etc.) are the best known of this class of teas. They are fermented (that is, aged) either naturally or using the Do Wui process developed by the Menghai and Xiaguan tea factories a few decades ago. Westerners call fully-oxidized teas by the term “black tea” but this is actually the true “black tea” (aka, “dark tea” or heicha).
Some heichas have several sub-versions and come from Anhui, Guangdong, Guangxi, Hubei, Hunan, Sichuan, and Yunnan provinces in China. Examples are Anhui Liu’an Lancha, Guangxi Liubao Cha, Hubei Laobian Cha, Hunan Heicha, and Sichuan Biancha. There is also Ddok Cha from South Korea and Japanese Awabancha and Goishicha.