shēng shú

Pu-erh exists in two fundamentally different forms — “raw” shēng chá (生茶) and “ripe” shú chá (熟茶). The line between them is neither the leaf grade nor the region, but a single technological fork, which took its final shape in 1973 when the Kunming Tea Factory perfected the method of accelerated microbial fermentation 渥堆 (wò duī).

Common foundation: 晒青毛茶

To understand the difference between shēng and shú, one must start with what they share — the raw material. Both types are made from the same semi-finished product called shài qīng máo chá (晒青毛茶), meaning “rough tea of solar drying.”

The production chain for this is as follows: fresh leaves of the Yunnan large-leaf cultivar (云南大叶种) undergo fixation 杀青 (shā qīng), then rolling 揉捻 (róu niǎn), and finally sun-drying 晒干 (shài gān).

The key and least obvious point here is the fixation regime and the nature of the drying. Unlike green tea, where 杀青 is carried out at a high temperature to fully deactivate the enzymes, the fixation for pu-erh is low-temperature: it merely slows down oxidation but preserves a portion of the enzymes and, more importantly, the leaf’s natural microflora. The drying is done in the sun, not in an oven (烘) or on a hot wok (炒).

This is precisely what makes 晒青毛茶 the base for pu-erh. Oven or wok drying, as used for green tea, would kill the microbial and enzymatic potential — and the material would never become pu-erh, no matter how long it lay afterward. Therefore, Yunnan sun-dried green tea goes not into green export bulk, but directly into pu-erh production: it has the inherent capacity for further transformation.

The fork: natural aging or 渥堆

The paths diverge from this common semi-finished product.

生茶 (raw pu-erh). The maocha is steamed and pressed into cakes (饼), bricks (砖), or tuo nests (沱), after which the tea is sent for natural aging in a dry warehouse (干仓) — for years. The microbial and oxidative transformation proceeds slowly, gradually changing the taste from sharp and green to soft and deep. This is the classic principle of 越陈越香 — “the older, the more aromatic.”

熟茶 (ripe pu-erh). Here, the maocha first undergoes 渥堆 — a wet pile in which, with the participation of water, heat, and microorganisms (primarily the black aspergillus 黑曲霉, Aspergillus niger), fermentation is artificially accelerated. The process lasts approximately 40 – 60 days, with regular turning of the pile (翻堆) to control temperature and humidity. This is followed by post-fermentation (后发酵), and only then is the tea steamed and pressed. The result is a tea that is ready to drink young, without long years of aging.

In other words, shú chá is an attempt to reproduce in one and a half to two months what shēng chá achieves over decades.

Why the revolution was needed

Before the 1970s, the “ripe” effect was achieved in only two ways: either by the natural aging of raw pu-erh over many years, or by the more aggressive “wet warehouse” (湿仓) practiced in Hong Kong, where high humidity accelerated the transformation. Both methods were slow, poorly controlled, and unpredictable in result.

The market — especially Hong Kong and the export market — needed a tea that could be drunk immediately: soft, dark, without the green sharpness of young shēng. The task was to learn how to obtain a “ripe” profile in a controlled and rapid manner.

1973: the birth of 渥堆熟茶

The pivotal year was 1973. At the Kunming Tea Factory (昆明茶厂), a team led by Wú Qǐyīng (吴启英), after a trip to Guangdong Province where the technique of “发水” (wetting the tea) was used, perfected the 渥堆 technology — controlled, accelerated microbial fermentation.

This was that very revolution: for the first time, “ripeness” ceased to be the result of random aging and became a reproducible production process.

By 1975, serial ripe pu-erh appeared. Two products became benchmarks:

• 7572 — a ripe cake from the Menghai factory (勐海);
• 7581 — a ripe brick from the Kunming factory.

At the same time, the 唛号 (mài hào) labeling system — recipe codes encoding the year of recipe development, the leaf grade, and the factory number — took hold.

A distinct figure in this history is Zōu Bǐngliáng (邹炳良) from the Menghai factory, who is called the “father of ripe tea” (熟茶之父) for the technological standardization of 渥堆. Later, in 1999, he founded his own production operation, Haiwan / Lao Tongzhi (海湾/老同志).

销法沱: an export milestone

Simultaneously, accelerated fermentation opened the door for pu-erh to the West. In 1976, the Xiaguan factory (下关) released xiāo fǎ tuó (销法沱) — a ripe tuo oriented for export to France. This was one of the first Chinese teas to receive certification as “organic” in the West.

The name literally means “tuo for sale in France” and cemented this product’s status as a pioneer of the European market.

Taste and brewing

The difference in technology translates directly into taste.

Young shēng is bright, invigorating, with a green and floral note, perceptible bitterness (苦), and astringency (涩), which soften over the years. Aged shēng becomes deep, with tones of dried fruit, wood, and “old warehouse.”

熟茶 produces a dark infusion of chestnut-red or almost black hue, soft and rounded, with earthy, woody, sometimes nutty and date-like tones, without the bitterness of young raw tea. The 勐海味 profile — the “Menghai taste” — is considered the benchmark, having become the tuning fork for the entire segment.

Ripe pu-erh is forgiving of boiling water and strong leaf dosage; it is conveniently brewed by repeated infusions in a gaiwan or Yixing teapot, with the first short infusion usually discarded to rinse the pressed leaf.

Modernity

Today, shú chá is a mass market segment of “ready-to-drink” tea that requires no long waiting. On its basis, a separate genre has grown: 柑普 / 小青柑 — ripe pu-erh encased in aged tangerine peel from Xinhui (新会陈皮), which experienced a boom in the 2010s.

How to distinguish sheng from shu

• Dry leaf color. Shēng ranges from green-gray to brownish with age; shú is uniformly dark brown, almost black.
• Infusion color. Raw gives a golden-yellow or (with age) amber infusion; ripe gives a rich red-brown, opaque-dark one.
• Taste. Bitterness, astringency, and fresh greenery point to shēng; softness, earthiness, and the absence of sharpness point to shú.
• Age and logic. Raw pu-erh is valued for its ability to age and improve over years; ripe pu-erh is initially created for immediate drinking.
• Origin of the technology. Any ripe pu-erh is a descendant of 1973: without 渥堆, it simply would not exist. Raw pu-erh, in its essence, is older than the industrial era.

The main thing to keep in mind: shēng and shú are not “young and old” versions of the same tea, but two different branches that diverged at a single point in the technological process. And that point is the pile of 渥堆, perfected in Kunming in 1973.