Processing Methods

A coffee bean is the seed of a fruit. Everything between picking that fruit and drying the seed is processing, and it shapes flavour as much as origin or variety does.

The cherry has, from outside in: skin, sticky fruit pulp (mucilage), a parchment layer, a silverskin, and the two seeds. Processing is about when and how each layer is removed, and how long the seed sits in contact with sugary, fermenting fruit.

Washed (wet process)

The skin and most of the pulp are stripped mechanically (depulped) within hours of picking. The remaining mucilage is removed by fermentation in tanks for 12–72 hours — microbes break down the sticky layer — then the parchment coffee is washed and dried on patios or raised beds.

• Cup: clean, bright, transparent. Acidity and origin character are front and centre.
• Brewing: the most predictable process. Extracts evenly and rewards high extraction.
• Where: Colombia, Kenya, most of Central America, much of Ethiopia.

Natural (dry process)

The whole cherry is dried intact, on beds or patios, for two to four weeks with constant turning. The seed ferments inside the fruit as the sugars concentrate, then the dried husk is milled off.

• Cup: fruit-forward — berries, wine, tropical fruit; heavier body, lower perceived acidity, more sweetness. Poorly managed naturals can taste fermented, boozy, or "barnyard".
• Brewing: naturals extract easily and tend to have more fines; go a touch coarser or cooler than a washed coffee of the same roast.
• Where: Ethiopia, Brazil, Yemen; increasingly everywhere.

Honey / pulped natural

Depulped like a washed coffee, but some or all of the mucilage is left on during drying. Named by how much is left: white/yellow honey (most removed) through red and black honey (nearly all left on, dried slowly in shade).

• Cup: in between — the sweetness and syrupy body of a natural with more of the clarity of a washed coffee.
• Where: Costa Rica, El Salvador, Brazil ("pulped natural").

Anaerobic and extended fermentation

Cherries or depulped beans are sealed in tanks with limited oxygen, sometimes with added yeast, fruit, or CO₂ ("carbonic maceration"). Fermentation runs for days under controlled conditions.

• Cup: intense and unusual — tropical fruit, cinnamon, rum, bubblegum, "funk". Divisive and expensive.
• Brewing: these are often brewed as espresso or with immersion methods where the intensity works; extract carefully as the fermented notes can turn harsh at high extraction.

Wet-hulled (giling basah)

Unique to Indonesia. The coffee is depulped, briefly fermented, then hulled from its parchment while still at 30–40 % moisture and dried as bare green beans.

• Cup: earthy, herbal, cedar, heavy body, very low acidity. Sumatra Mandheling is the archetype.
• Brewing: suits darker roasts, immersion, and milk; rarely rewards light-roast pour over treatment.

Decaffeination

Not a processing method in the same sense, but it happens to green coffee. Swiss Water and mountain water processes use water and carbon filters; sugarcane / EA process uses ethyl acetate derived from sugarcane and preserves sweetness well; CO₂ process uses supercritical CO₂. Decaf green coffee is browner and more fragile, roasts faster, and is easier to over-roast — brew it a little cooler.

Matching process to recipe

The recipe library lets authors specify a preferred process. As a rule of thumb:

Process	Flatters
Washed	pour over, high-ratio, hot water, clarity-focused recipes
Natural	immersion, espresso, bypass recipes that tame intensity
Honey	almost anything; especially AeroPress and Kalita
Anaerobic	espresso, cold brew, AeroPress concentrate
Wet-hulled	French press, moka, cold brew, milk drinks