Wet hulled
Why remove the parchment before drying is finished?
Start the scene or choose a stage. The animation simplifies the mechanism; what follows gives the details and the available references.
In Indonesia, the coffee is pulped and briefly fermented: overnight, in a concrete tank or in plastic rice sacks, according to Lynch's field description.
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- Ferment overnightIn Indonesia, the coffee is pulped and briefly fermented: overnight, in a concrete tank or in plastic rice sacks, according to Lynch's field description.
- Dry in parchment for two to three daysWashed, the coffee dries in parchment for two to three days, no more: it stops well before it is dry. Under 70 to 90% relative humidity and some 2,000 millimeters of rain, drying in parchment would take weeks, enough time for mold to set in.
- Hull while still wetA semi-dry parchment is hulled with high friction, which no other country does; it does not break, it tears. At what moisture content? The sources contradict one another, from 20 to 24% at Lynch to 30 to 50% in commercial sources, by way of 30 to 35% for the Indonesian association, Marsh and Hoffmann.
- Finish on the naked beanThe naked bean, soft and swollen, dries two to three times faster, down to 12 or 13%, in the sun by day and bagged indoors at night, where it keeps fermenting. It comes out blue-green to opal, swollen, irregular.
To remember: It is a technique of economic survival: the climate rules out long drying in parchment, and the producer sells within a few days to a collector who takes over the drying.
In history: The historical origin, VOC, 19th century or Aceh of the 1970s, rests only on commercial blogs.
Read the full article and its sources ↓
| Process | What is removed before drying | What it gives |
|---|---|---|
| Dry, natural | nothing | fruity, body, risk of foul-smelling beans (stinkers); the coffee berry borer completes its cycle |
| Washed | skin, pulp, mucilage | clean, acidic; kills the coffee berry borer |
| Honey, pulped natural | skin, part of the mucilage, or nothing more than the skin | a third thing, with phenolamides of its own |
| Wet hulled | skin, mucilage, then the parchment while wet | heavy body, low acidity, earthy |
| Monsooned coffee | dry natural, then monsoon winds | body, muted acidity, spices |
In Indonesia, the coffee is pulped, briefly fermented, partially dried in parchment, then hulled while the coffee is still decidedly wet, which no other country does; the naked bean, soft and swollen, finishes drying in the open air. The parchment does not break, it tears. Two material reasons, unrelated to taste: the climate, 70 to 90% relative humidity all year round and some 2,000 millimeters of rain, where drying in parchment would take weeks during which mold would set in, whereas the naked bean dries two to three times faster; and cash, the producer selling within a few days to a collector who takes over the drying instead of tying up his harvest for weeks. It is a technique of economic survival.
Lynch, Perfect Daily Grind, October 21, 2015; Marsh, Review of the Aceh Coffee Industry (2006); Hoffmann, The World Atlas of Coffee, 2nd ed. (2018); LC ch. 17bOn wet hulled (giling basah, in Indonesian), the sources flatly contradict one another on one precise point: at what moisture content is the coffee hulled?
- 30 to 35% for the Specialty Coffee Association of Indonesia in 2008, Marsh in 2006 and Hoffmann in 2018;
- 30 to 40%, or 35 to 40%, among the traders Sucafina and DRWakefield;
- 30 to 50% in various commercial sources;
- and 20 to 24% at Lynch.
The last gap is too large to be a mere imprecision. From one source to another, the bean being hulled is not in the same state. And it is Lynch's description that is the most detailed from the field, because it comes from on-site observation. Here it is in full.
- Fermentovernight, in a concrete tank or in plastic rice sacks.
- Wash, then dry in parchmenttwo to three days, no more: it stops well before the coffee is dry.
- Hullthe hulling is done at high friction, on semi-dry parchment.
- Finish drying on the naked beandown to 12-13%, in the sun by day, bagged indoors at night.
This last detail matters more than it seems: bagged warm overnight, the bean keeps fermenting. The method therefore prolongs fermentation without saying so.
The result is recognizable among all others. The green coffee is blue-green to opal, swollen, irregular, porous. In the cup: a syrupy, heavy body, very low acidity, little sweetness, earthy, woody, herbaceous, sometimes moldy notes.
The signature defect has a name, the goat's nail (kuku kambing, in Indonesian): a hoof-shaped split, caused by the crushing of the still-soft bean at hulling.
Two reservations to finish. The mechanism put forward, the direct exposure of the kernel to microorganisms once the parchment is removed, is plausible and claimed, but it has not been measured. And the historical origin of the process, traced back now to the VOC, now to the nineteenth century, now to the Aceh of the 1970s, rests only on commercial blogs.
Lynch 2015; Marsh 2006; Hoffmann 2018; Zhang et al. 2019 for the effect of pulping on earthy notes; LC ch. 17b