Blog
Wet-Hulled Coffee: How the Giling Basah Process Works
Follow wet-hulled coffee from pulping to final drying. See how giling basah differs from washed coffee and what the process tells you about a bag.
Quick Answer
Wet-hulled coffee has its parchment layer removed while the seed is still relatively moist, then finishes drying as exposed green coffee. In conventional washed processing, the seed finishes drying inside its parchment before hulling. This change in sequence distinguishes giling basah, the Indonesian term commonly used for wet hulling.
On This Page8 Sections
Which Layer Comes Off?
Parchment is the protective layer around the coffee seed, beneath the fruit's pulp and sticky mucilage. Pulping removes the outer fruit material; it leaves parchment around the seed. Hulling removes that remaining cover.
The JICA Rwanda processing protocol distinguishes those layers. A coffee can therefore be pulped and washed while still drying “in parchment.”
The Wet-Hulling Sequence
After harvesting and sorting, a simplified wet-hulled pathway is:
- Pulp the cherries. Remove the outer skin and fruit flesh.
- Handle the mucilage. Fermentation and washing can remove the sticky material around the parchment.
- Partly dry the parchment coffee. The cover remains on during this initial drying.
- Hull while the coffee is still relatively moist. Remove the parchment.
- Finish drying the exposed green beans. They still need this stage before storage.
The key comparison is when hulling happens:
| Process | Drying and hulling order |
|---|---|
| Conventional washed coffee | Finish drying in parchment, then hull. |
| Wet-hulled coffee | Partly dry in parchment, hull, then finish drying the exposed beans. |
Washing and hulling describe different operations. A coffee can be washed earlier in processing and still be wet-hulled later. The processing methods guide places this sequence alongside natural, honey and other washed pathways.
What Early Hulling Changes
Removing parchment changes the surface exposed during the rest of drying and handling. A 2013 water-transport study examined parchment, silverskin and the seed's endosperm as distinct structures and highlighted parchment's protective contribution.
For a lot description, follow the green beans beyond the huller. Who completed the drying, and how was the coffee handled afterward? Hulling and readiness for storage are separate milestones.
How Wet Is the Coffee at Hulling?
The JICA protocol describes 30–40% moisture at wet hulling. A FAO-hosted North Sumatra field report describes a huller modified to handle parchment at 35–45%, compared with its 11–14% dry-parchment design range.
Keep those figures with their sources. The quoted passages do not state their wet- or dry-basis convention, so the ranges cannot be treated as a matched measurement or a single operating target.
Why the moisture basis changes the percentage
On a wet basis, water is divided by the sample's total mass. On a dry basis, water is divided by its dry matter.
For a hypothetical 100 g sample containing 30 g water and 70 g dry matter:
- Wet basis: 30 ÷ 100 × 100 = 30%.
- Dry basis: 30 ÷ 70 × 100 = 42.9%, rounded.
This is the same sample with two denominators. The example explains the labels; it does not set a hulling condition. The water activity and moisture guide explains the related measurements.
What Does Wet-Hulled Coffee Taste Like?
Earthy and herbal descriptions are familiar for some Indonesian coffees. Use a roaster's description of the particular lot to learn whether it leans toward those notes, a spicy character, sweetness or another profile.
In the North Sumatra field trial, seven processing treatments across six coffee sources produced 42 samples. Tasters found Mandheling character in some samples, but the results did not consistently link it to one treatment. That makes the report a useful check on claims that one wet-storage step guarantees the regional flavor.
Mustiness is not a required sign of authenticity. The Sumatra guide covers regional differences and choosing a coffee for the flavors you enjoy.
A personal note: I find process names easier to remember when I can picture a sequence. With wet-hulled coffee, the image that stays with me is the seed leaving its parchment while drying is still unfinished. It gives me something concrete to ask about when I read a bag description: what happened next, and who completed that stage? I can enjoy earthy or herbal tasting notes without treating them as a checklist every wet-hulled coffee must match. Following the coffee through the work interests me more than making it fit a reputation.
Reading Process Names on a Bag
- Semi-washed: ask how the mucilage was handled and when the parchment came off. Sucafina's origin handbook separates those processing decisions.
- Wet processed: this description can leave the timing of parchment removal unclear. Check whether drying finished inside the parchment.
- Wet-hulled Sumatra: this gives a processing approach and island origin. The producer or lot, roast and tasting description help you choose the actual coffee.
A clear account lets you follow the sequence through to the finished green coffee, including the final drying after the parchment leaves.
Sources
- JICA Rwanda CUP2, coffee processing protocol, Kigali 2025
- Anthony Marsh, Storage of wet Arabica parchment prior to wet hulling, FAO project field report
- Ramírez-Martínez et al. (2013), Water transport in parchment and endosperm of coffee bean
- Sucafina Origin Handbook 2021, glossary of processes