Reference · processing methods

Coffee processing methods: washed, natural, honey and more

The “process” line on a coffee bag names what happened at the farm or mill between picking the ripe cherry and shipping the dry green bean. Here is what each method removes from the fruit, fermentation and drying times, moisture targets, and how sources describe the cup.

Updated 2026-11-06 · sources listed at the end · no product recommendations

What processing has to do

A coffee bean is the seed of a fruit. Around it sit, from the outside in, the skin, the fruit flesh (pulp), a sticky layer called mucilage and a thin husk called parchment. The National Coffee Association (NCA) says picked cherries should be processed “as quickly as possible to prevent spoilage”. Every method ends the same way: a dry green seed, typically around 11% moisture, with all layers removed. The methods differ in which layers are still on the seed while it ferments and dries.

Skin — only natural (dry-process) coffee dries with the skin on.
Pulp (fruit flesh) — removed by the pulper in honey and washed processing.
Mucilage — the sticky layer honey coffee dries with; washed coffee loses it by fermentation and washing or by machine.
Parchment — washed coffee dries in it; it is hulled off at the dry mill.
Seed — in wet-hulling the parchment comes off at 40–45% moisture, so the bare seed finishes drying.

Drawn by pourxlab after the NCA processing guide, the IFT article and Wikipedia’s coffee production article. Anaerobic and other fermentation variants can start from any of these states. Not to scale.

The methods at a glance

Method	On the seed while drying	Typical timing	How sources describe the cup
Washed (wet)	Parchment	Ferments 12–48 h in tanks (NCA), then dries to about 11%	“Clean”, floral, citrus (NCA); “clean, balanced” with “fruity acidity” (IFT)
Natural (dry)	Whole cherry	Up to four weeks of drying to 11% (IFT)	Fuller body, sweet and fruity, can taste winey (NCA); “smooth and heavy-bodied” (IFT)
Honey / pulped natural	Mucilage + parchment	8–10 days (yellow) to about 30 days (black) of drying (Wikipedia)	“Rounder in acidity”, more chocolate, a bit sweeter than washed (Coffee Review)
Wet-hulled	Bare seed after hulling	Hulled at 40–45% moisture, then dried to about 13% (Wikipedia)	Low acidity, heavy body, spicy and earthy notes (Wikipedia, of Sumatran Mandheling)
Anaerobic	Any of the above	Sealed with little oxygen for about one to six days before drying (Coffee Review)	More intensity, fuller body, tangy lactic notes (Coffee Review)

The Institute of Food Technologists (IFT) article states that processing “is considered to be the single largest contributor to the flavor profile of coffee,” ahead of microclimate and soil.

Step by step: the washed process

Pulp the cherries fast. A 1966 University of Hawaii extension guide for Kona growers says to pulp the same day if possible and within 24 hours.
Sort. The NCA describes flotation in water, where lighter, unripe beans float, then sorting by size in rotating drums.
Ferment off the mucilage. Beans sit in water-filled tanks for 12 to 48 hours (NCA); IFT gives 16 to 36 hours and Wikipedia 12 to 36. The Hawaii guide says warm climates can finish in under 12 hours, cool ones may take two days or more, and fermentation is done when the beans “are no longer slippery.” Machines can scrub the mucilage off instead, which saves water (IFT).
Wash with clean water.
Dry in parchment on tables, floors or in mechanical dryers to about 11% moisture (NCA). The Hawaii guide reports four to six days of sun in good weather.
Rest and hull. The same guide rests dried parchment at least 10 days before hulling.

The University of Hawaiʻi’s “Coffee at Home” sheet scales this down for backyard trees: squeeze the fruit to free the seed, cover with water overnight, rinse the next day, sun-dry until the bean inside the parchment is “hard to bite,” and rub or pulse the parchment off.

Natural and honey coffees

For naturals, whole cherries are spread on large surfaces, raked and turned through the day and covered at night or in rain until they reach 11% moisture, which “could take several weeks” (NCA). Wikipedia says about 90% of Brazilian arabica and nearly all robusta are dry-processed, as is coffee from Ethiopia, Haiti and Paraguay. The NCA warns that drying ripe and unripe fruit together gives uneven quality.

Honey coffee keeps some or all of the mucilage. The NCA says more mucilage generally means a sweeter cup closer to a natural, less means a profile closer to washed. Coffee Review’s Kenneth Davids notes the term “pulped natural” was first coined in Brazil and is often used for the same thing. Central American mills grade honeys by how much mucilage stays on:

Grade	What it means	Drying time
Yellow honey	Less mucilage left; beans dry golden (Coffee Review)	8–10 days
Red honey	Relatively thick mucilage that takes a reddish cast (Coffee Review)	12–15 days
Black honey	Darkest drying; at one Costa Rican mill, very sweet fruit from the peak of harvest (Coffee Review)	about 30 days

Drying times are Wikipedia’s figures; the names are mill usage, not a standard.

Wet-hulled and anaerobic coffees

Smallholders in Sumatra, Sulawesi, Flores and Papua wet-hull: parchment coffee is sun-dried for half a day to two days, hulled at 40–45% moisture, dried three to five days to 14–17%, and taken to about 13% later (Wikipedia).

Anaerobic coffees ferment in sealed bags or tanks with limited oxygen; in “carbonic maceration” extra CO₂ is injected. Coffee Review explains that with less oxygen, yeasts are suppressed and bacteria become more active, which it links to tangy lactic notes. The fruit stays sealed “for anywhere from around one day to six days” and can then be dried as a natural, honey or washed coffee.

Drying and moisture: the numbers

Figure	Value	Source
Washed coffee leaving the wet mill	about 53%	Wikipedia
Drying target	about 11%	NCA, IFT
Stable range	10–12%	Wikipedia
Kona parchment after drying	11.5–13.0%	Hawaii guide, 1966
Kona green coffee	9.5–11.0%	Hawaii guide, 1966
Specialty, premium and exchange grades	9–13%	FAO Annex 7
Mass too hot while drying	above about 40 °C parchment, 45 °C cherry	Wikipedia

IFT notes that drying “determines the final quality of the green coffee”: overdried beans turn brittle and underdried beans deteriorate.

Where the sources disagree

Most common method. IFT calls dry processing “the oldest and most common method”; Wikipedia cites the International Trade Centre describing washed as the most common of the three.
Fermentation time. 12–48 h (NCA), 16–36 h (IFT), 12–36 h (Wikipedia), under 12 h in warm Kona weather (Hawaii guide).
Moisture. Around 11% (NCA, IFT), 10–12% (Wikipedia), 9–13% across FAO’s grade tables.
Black honey. Defined by drying time in Wikipedia, by fruit selection at one mill in Coffee Review.

Newer research moves away from the three classic labels. A 2023 review by Ferreira and colleagues proposes grouping processes by fruit treatment, oxygen, added water and starter cultures, and concludes “it is not possible yet to define a single process capable of increasing coffee quality.” In one 2024 study of a single Brazilian cultivar, naturals given a 96-hour self-induced anaerobic fermentation scored 87.50 points against 83.30 for the unfermented natural control (Silva et al.).

What it means when you brew

Processing is fixed before the beans reach you, and none of the sources above gives separate brew settings by process. Treat the process line as a hint about flavor, not a recipe: brew a new bag at your usual ratio, taste, and change one variable at a time with the taste troubleshooting chart. To learn what “natural” or “honey” tastes like, cup a washed and a natural coffee side by side using the home cupping method.

Checklist: reading the process line on a bag

Washed or wet: parchment-dried; sources expect a “clean” cup.
Natural or dry: dried in the whole fruit; expect more body and fruit.
Honey, pulped natural or semi-washed: some mucilage left; yellow, red and black are mill grades.
Wet-hulled or giling basah: usually Indonesian; low acidity and heavy body are typical descriptions.
Anaerobic or carbonic maceration: a sealed fermentation step added to one of the above.
Note the process next to roast level and roast date in your brew log so you can compare bags.