Lesson 8/5 : Black Tea Processing

Black Tea – Origin and History

My Little Tea School - The ABC of TEA, Lesson 8/5 - Black Tea Processing
Invention of Black Tea Processing in China

Like everything in the world of tea, the method of processing tea leaves into black tea originates from China. When exactly it was first invented remains a popular subject among scholars to discuss. However, we do know that towards the end of the 17th century Dutch traders brought black tea from China to Europe for the first time. Specifically, this was Lapsang Souchong from Wuyishan, Fujian. Accordingly, we can assume that black tea had already been known there for a while by then. Amazingly, what we call black tea in Europe goes as “red tea” (“hong cha”) in China. The reason for this is the reddish color of black tea in the cup.

Schwarzer Lapsang-Tee (Wuyishan)
Black Lapsang Tea (Wuyishan)
Black Tea Conquers Europe

In Europe, black tea very soon prevailed over green tea. The reason for this is obvious … During the processing of black tea the tea leaves undergo an oxidation process that besides changes in taste changes also causes better preservability of the processed tea. So while green tea suffered greatly from the long journey in moldy, damp ship’s holds, black tea made the journey without any loss. That’s why green tea was rather a rarity in Europe until well into the second half of the 20th century. Black tea, on the other hand, rapidly conquered Europe and became the foundation of all European tea cultures.

Black Tea – Places of Origin

After its discovery in Fujian, the method of black tea processing quickly spread to other regions of China. Other well-known examples besides Wuyishan’s Lapsang teas are “Dian Hong Cha’s” from Yunnan and Keemun teas from Anhui. Also, many producer countries outside of China traditionally produce and export black tea in order to serve the demand on the world market. Classic examples of this would be the large tea growing regions of India, Darjeeling and Assam, as well as Sri Lanka (Ceylon teas). However, also younger tea growing regions such as Kenya supply the European market and therefore focus on producing black tea.

The World Map of Tea - Painted by Artist
The World Map of Tea – Tea Origins

Black Tea Processing

According to legend, the invention of the black tea processing method, involving the full oxidation of the tea leaves, goes back to a coincidence. At the time, a village in Wuyishan’s Lapsang region allegedly was attacked by enemies. So it came that the freshly picked tea leaves, actually intended for processing into green tea, were left alone. As a consequence, they oxidized, and the result was subsequently found to be very tasty. Well, it could have happened this way. However, from freshly picked tea leaves to black tea as we know it, it takes more than just leaving the tea leaves alone…

Black Tea Processing - Overview of the 4 major processing steps
Black Tea Processing – Overview
click to enlarge

Essentially, black tea processing consists of 4 processing steps:

1. Withering

As for all types of tea (green tea being a bit of special case) black tea processing begins with the withering of the tea leaves. Depending on local traditions and type of tea, there are basically two possible settings for withering tea leaves in black tea processing. One of these is indoor withering in so-called withering troughs. The other is the withering outdoors on lathes covered with jute, wire or nets. In most cases, however, it will be a combination of both – first outdoor, then indoor. In any case, essential is a good ventilation, so that fresh air can unimpededly reach the tea leaves. For this purpose, these are spread in a thin layer. Optional at this is additional heat feed, accelerating the withering process.

During withering, the tea leaves gain in suppleness, which is beneficial for the further processing. Also, they lose about 30% of their moisture content in this step.

2. Rolling

The purpose of rolling the tea leaves is to break up the cell walls in the tea leaf and on its surfaces through mechanical force. This can either be done manually (eg in the wok pan or a comparable device) or by machine. On the one hand, the tea juices can cevenly distribute in the leaf this way. On the other hand, tea juices leak at the break lines on the leaf surfaces, where they react with oxygen from the air. For an optimal result, the rolling process is repeated several times. With best (artisan) practice, the tea leaf is preserved as a whole during this process.

A special form of processing black tea is the so-called “CTC” (curl-tear-crush) method. Here, the tea leaves undergo one rolling cycle only before being wrenched and ground by machine. The result represents a large share of the tea world market for two reasons. On the one hand, CTC tea can be accommodated in a tea bag. On the other hand, in this form the tea releases its taste and active ingredients in hot water comparatively quickly. And in just one steep! “Convenience” is a keyword here, “cheap” is a second … Because, firstly, the method does not impose high quality requirements on the leaf material. And, secondly, it enables a relatively uncomplicated, continuous mechanical process. Well, and the tea bag – as detrimental as it may be to real tea enjoyment – unfortunately still shapes the mass market in our fast-paced world.

3. Oxidation

In fact, the oxidation process, the reaction of the cell juices with the oxygen from the air, already starts during rolling. After completion of this, the tea leaves are spread in about 10-15cm thick layers. Often shelf-like devices inside the processing hall serve for this purpose. At an optimum room temperature of 40°C, the oxidation process can take several hours. During this time, the tea leaves take on a coppery to brown color. For the first time now the aroma of the tea begins to unfold. Altogether, this processing step is particularly coining the flavor of the black tea.

4. Drying

The tea master determines when the oxidation process has reached its peak and the tea leaves have reached the optimum flavor and taste level. Then, initial drying at a relatively high temperature (around 90°C) in a hot air dryer or other, more traditional device, stops the oxidation. In the further course of the drying process, gradual lowering of the temperature ensures the gentle preservation of the previously fixed taste and aroma.

In the course of this processing step, the tea juices emerged on the leaf surfaces during rolling dry on the leaf. At the same time, the tea leaves take on the dark color characteristic of black tea.

Jun Chiyabari Himalayan Black - Black Tea from Nepal
Jun Chiyabari Himalayan Black – Black Tea from Nepal

As a fifth step, we could optionally name the separation of the “wheat from the chaff”, ie the sorting out of inferior quality or damaged tea leaves. This can take place by manual picking or by means of special riddle screens. However, this is not a processing step in the strict sense .

Royal Tippy Latumoni - Black Tea from Assam
Royal Tippy Latumoni – Black Tea from Assam

One more thing, on my own account…

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