Processing Method

Wet Hulled Coffee (Giling Basah)

Wet hulling (Giling Basah in Indonesian) is the processing method that gives Sumatra its signature character—earthy, full-bodied, low acidity, with that distinctive "blue" appearance. For roasters who want that profile, understanding wet hulling is essential to buying well.

By Samuel Demisse — 3× U.S. Coffee Tasters Champion, Q-Grader, 34 years in specialty coffee

Hulled wet Earthy profile Low acidity Full body

TL;DR for Roasters

Before you buy wet hulled

Wet hulled coffees deliver a specific flavor profile that customers either love or don't understand. Know what you're buying and why.

When wet hulled makes sense: Customers want "Sumatra character." Blend needs earthy bass notes. Dark roast program needs body without bitterness.
When to consider other origins: Customers expect bright acidity. Light roast program. Single origin needs to be "clean" or "transparent."
What can go wrong: Over-fermented lots (dirty, musty). Inconsistent moisture (hulled too wet). Past-crop taste (stored poorly).

Four specs to require

  • 1 Moisture at hulling: Wet hulled at 30–35% moisture (not dried to 12% first).
  • 2 Final moisture: 10–12% at export. Check arrival moisture too.
  • 3 Defect count: Grade 1 Mandheling = ≤8 full defects per 300g (local standard; Ethiopian Grade 1 washed is ≤3).
  • 4 Cup sample: Earth without mustiness. Herbal without dirty. Full body without harshness.

We cup every Sumatra lot before and after arrival. Request samples →

The Basics

What "wet hulling" means

In wet hulling (Giling Basah), coffee is hulled while still wet—at 30–35% moisture instead of the 10–12% used in other processes. The parchment is stripped off early, and the bare green bean finishes drying exposed to air.

This happens because Indonesia's high humidity makes parchment-drying slow. Farmers sell parchment wet to collectors, who hull and finish drying. The exposure creates the distinctive flavor and blue-green color.

Quick specs

  • Hulling moisture: 30–35% (not fully dry)
  • Final drying: Green bean exposed to air
  • Appearance: Blue-green, softer bean
  • Cup: Earthy, herbal, low acidity, full body

The Process

How wet hulling works

01

Pick and depulp

Farmers depulp cherry same day, like washed process.

02

Ferment briefly

Overnight fermentation in bags or tanks. Mucilage loosens.

03

Wash and partial dry

Wash off mucilage. Dry parchment to 30–35% moisture.

04

Sell to collector

Farmers sell wet parchment. Collectors aggregate lots.

05

Wet hull

Parchment removed while wet. Green bean exposed.

06

Final drying

Bare green bean dries to 10–12%. Develops signature color and flavor.

Flavor

The wet-hulled profile

When it's clean

Cedar, tobacco leaf, dark chocolate. Herbal complexity without mustiness. Syrupy body. Smooth, almost muted acidity.

When it goes wrong

Musty, moldy, dirty. Baggy or past-crop. Harsh, medicinal. These are process failures, not "Sumatra character."

Roast behavior

Lower density, more moisture uptake. Benefits from longer development. Works well into dark roasts without becoming bitter.

What Sumatra is not

Wet hulling creates a specific profile—earthy, herbal, low acid, full body. If you want bright citrus or berry fruit, Sumatra won't give you that. Choose origins like Ethiopia, Kenya, or Colombia instead. Browse Ethiopia coffees →

Connecting Flavors

Sumatra as a gateway coffee

Customers who love Sumatra often respond well to Ethiopia Harrar. Harrar is a natural Ethiopian with similar earthy, winey notes but more fruit complexity. It's a bridge from "Sumatra lovers" to "Ethiopian explorers."

Current Inventory

Sumatra coffees in stock

Inventory updating—request samples and we'll share current Sumatra availability.

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Ready to taste Sumatra?

Free samples—green or roasted. We'll help you find clean wet-hulled coffees that deliver the profile without the defects.