Withering, Reddening, and Yellowing: Common Faults in Pu'er Processing
Much of what makes a pu'er good or bad is decided at the maocha stage. When one step of processing goes off course, the traces remain in the dry leaf, the liquor, and the spent leaf, and some can still be tasted years later. Learning to recognize these faults isn't about nitpicking. It helps us better appreciate the work behind a cake of tea.
What Yunnan's Group Standard Says
The 2021 group standard Sun-Dried Tea (Large-Leaf Variety) from the Yunnan Tea Circulation Association explicitly excludes several practices:
- Withering: letting fresh leaves lose a lot of moisture and begin to oxidize.
- Long low-temperature kill-green: firing at too low a temperature for too long.
- Sealed yellowing (menhuang): piling and covering leaves after kill-green or rolling so they turn yellow.
- Reddening (wohong): letting leaves heap up, heat, and turn red.
- Tossing (yaoqing): an oolong technique of bruising leaf edges to promote oxidation.
All of these cause leaves to oxidize or change early at the maocha stage. The aroma may be more immediately appealing, but it strays from the true character of sun-dried green maocha.
Where Red Stems and Leaves Come From
When the stems, veins, or whole leaves in the spent leaf are reddish brown, common causes are:
- Fresh leaves left too long: crammed in baskets after picking or spread too thickly, the leaves heat up and redden.
- Over-spreading: close to withering, the leaf edges begin to oxidize.
- Incomplete kill-green: the wok isn't hot enough or the time is too short, so the enzymes aren't fully stopped and oxidation continues during rolling and sun-drying.
- Stems not fully fixed: large-leaf stems are thick and hold a lot of water, so they're the most likely to end up cooked outside and raw inside.
A few red stems aren't much cause for concern. But if there are many red stems and leaves, the liquor often tastes stuffy or carries a black-tea-like sweetness.
Where Smoke and Scorch Come From
- Scorch: the wok is too hot during kill-green or the leaves aren't tossed evenly, so they stick to the wok and burn. The dry leaf has black spots and the spent leaf has scorched edges.
- Smoke: smoke blows back during wood-fired kill-green, or the leaves are spread and dried indoors where there's smoke and absorb it. In the old days, when mountain households used wood stoves and dried tea by the fire pit, a smoky note was not unusual.
Some tea drinkers accept a light smokiness and even find it evokes the mountains, but it's a foreign smell, not the tea's own aroma.
What Is Sealed Yellowing?
Sealed yellowing is the key step in making yellow tea: after kill-green, the leaves are heaped and wrapped while still hot so they slowly turn yellow in the heat and moisture. In pu'er, it's a fault, and it typically happens when:
- Leaves are left heaped together too long after kill-green instead of being spread out.
- Clumps aren't broken up promptly after rolling, so the center of the ball stays hot and stuffy.
- In the rainy season, the leaves can't be sun-dried and wet tea is heaped indoors.
Pu'er with sealed yellowing has dull yellowish dry leaf, a stuffy, cooked taste in the liquor that isn't crisp, and a muddy aroma.
Other Common Faults
| Fault | Cause | Trace |
|---|---|---|
| Sourness | Left too long after rolling, not dried fully, heaped and stuffy | Sour, unclean liquor |
| Greenness | Incomplete kill-green, insufficient spreading | Grassy, raw and harsh |
| Damp stuffiness | Shade-drying in the rainy season, high moisture | Stuffy liquor, closed aroma |
| Fire | High-heat oven drying instead of sun-drying | High but parched aroma with a roasted note |
Do These Faults Disappear with Aging?
They need to be considered separately:
- Mild greenness and harshness: often fade after a few years in storage, blending into other aromas.
- Mild stuffiness and damp notes: may lessen when stored somewhere with good ventilation.
- Scorch and smoke: fade, but rarely disappear completely and may still be tasted in old tea.
- Changes from red stems and leaves and from withering: oxidation that has already happened can't be reversed, and the tea ages in a different direction from normal sun-dried tea. Tea drinkers often say it's "nice when young, flat when old."
- Mold: won't improve with storage. Don't drink moldy tea.
So "it'll get better with time" isn't a magic fix. Tea that starts out clean gives aging a good starting point. See Aging and Vintage in Pu'er.
How to Practice Spotting Them
After brewing, empty the spent leaves onto a white plate and spread them with your fingers: check whether the color is even and whether there are red stems or scorched edges. Then smell the cooled spent leaf, where off-notes stand out clearly. A full guide to off-flavors and faults is in Off-Flavors and Faults: Smoke, Sourness, Stuffiness, Damp, Foreign Odors. For the correct way to do kill-green and spreading, see Iron-Wok Firing vs. Drum Kill-Green and Spreading Fresh Leaves.
FAQ
Where do red stems and leaves come from? Fresh leaves left too long, over-spreading, or incomplete kill-green let the leaves oxidize and redden during processing.
Where do smoky and scorched notes in pu'er come from? Scorch comes from an overheated wok during kill-green; smoke usually comes from wood fires or smoke absorbed by the leaves.
What is sealed yellowing? Leaves heaped and left stuffy too long after kill-green or rolling turn yellow in the heat and moisture, giving the liquor a stuffy, cooked taste.
Do these faults disappear with time? Mild greenness and stuffiness may fade; scorch and smoke rarely disappear completely; oxidation and mold won't be undone by storage.