From cherry to green

Every coffee is a seed taken out of a fruit and dried. The methods differ in what is removed first, how long microbes work on it, and how much water it costs. Read the board left to right.

Methods: 17
On the board: 11
Decaffeination: 5
Most common: Washedlisted by 27 origins

The journey

Dots mark the stations a method uses

Washed (wet, fully washed)

Full method

Float and sort ripe cherry in water
Mechanically pulp to remove skin and most flesh
Hold pulped seeds in tanks so microbes degrade the pectin-rich mucilage (6-48 h, water-submerged or dry)
Wash and grade in channels to remove loosened mucilage
Dry parchment on patios, raised beds or in mechanical driers to 10-12% moisture
Rest, hull parchment, sort and grade

Dried to: 10–12%moisture
Fermentation: 6–48 h
Drying: 2–15 days
Water use: High
Cup tendencies: clean, bright acidity, consistent; fewer fermented or vinegary notes because soluble fermentation products are rinsed away
Risk: Over-fermentation and sour or onion defects if tanks run too long or too warm; heavy water demand and acidic wastewater from pulping and washing

Side by side

Ranges as published in each method's sources

Method	Water use	Fermentation	Drying	Cup tendencies	Origins
Washed (wet, fully washed)	High	6–48 h	2–15 days	clean, bright acidity, consistent; fewer fermented or vinegary notes because soluble fermentation products are rinsed away	27
Natural (dry process)	Low	none as a step	10–21 days	heavier body, enhanced sweetness, fruit-forward and wine-like complexity; less clarity than washed	17
Honey process (yellow, red, black)	Medium	none as a step	8–20 days	sweetness and body increase from yellow to black; red and black honey scored higher for mouthfeel and balance in one sensory study; washed and dry lots showed more bitterness and astringency	5
Pulped natural (semi-dry)	Medium	none as a step	7–15 days	more body and sweetness than washed, cleaner than natural; lower acidity	1
Wet-hulled (Giling Basah)	Medium	8–24 h	5–12 days	low acidity, heavy body, earthy, herbal and spicy character; bluish-green beans	1
Anaerobic fermentation, washed	Medium	24–96 h	7–15 days	intensified fruit, wine-like and lactic notes; anaerobic lots scored higher for mouthfeel and balance in one study	—
Anaerobic fermentation, natural	Low	24–120 h	14–30 days	very pronounced fruit, boozy and tropical notes layered over natural-process body	—
Carbonic maceration	Low	24–120 h	7–25 days	intact-fruit intracellular fermentation gives bright red-fruit, candy-like and sometimes bubblegum notes	—
Lactic fermentation	Medium	24–96 h	7–15 days	creamy, yoghurt-like acidity, fruity and floral notes; lactic acid bacteria produce malic and tartaric acids and caramel-honey aromas	—
Yeast-inoculated (starter culture) fermentation	Medium	24–72 h	7–15 days	more predictable fruity, floral and caramel notes; starters with high pectinase activity shorten mucilage removal	—
Thermal shock fermentation	Medium	none as a step	not published	producers report heightened aromatic intensity; not characterised in peer-reviewed sensory work found for this project	—

"Origins" counts the producing countries in this atlas that list the method as common. Timings are the ranges reported in the studies and producer sources cited on each method's page; a given lot can fall outside them.

After the mill

Post-processingMonsooned Malabar

Monsooned Malabar recreates the flavour that sea voyages once gave Indian coffee. Dry-processed green beans are exposed to the humid monsoon winds in ventilated warehouses on India's west coast for several months, swelling, turning pale and losing almost all acidity. The Coffee Board of India markets the top grade as Monsooned Malabar AA and notes that only dry-processed arabica and robusta are used and that the coffee is mostly blended to add body and mellow sharper coffees.

Decaffeination

Done to green coffee, before roasting

Water use mediumEthyl acetate (sugarcane) decaffeination

Ethyl acetate decaffeination is a direct-solvent method in which steamed beans are washed with ethyl acetate, an ester that occurs naturally in fruit and is produced industrially by fermenting sugarcane molasses to ethanol, hence the 'sugarcane decaf' label used for the Colombian plants. The solvent is then steamed off. It is cheaper than CO2 and water methods and retains sweetness well, but it remains a chemical-solvent process subject to residue limits.

Water use mediumMethylene chloride (dichloromethane) decaffeination

Methylene chloride, also called dichloromethane, is the classic decaffeination solvent used since the mid-twentieth century in direct and indirect (water-extract) variants. It is efficient and inexpensive and the solvent is almost entirely removed by steaming and roasting, but its toxicity profile has made it the method most criticised in the literature and the market, and it drives demand for CO2, water and ethyl acetate alternatives.

Water use mediumMicrobial and emerging decaffeination

Researchers are testing biological and physical alternatives to solvent decaffeination. More than 120 microorganisms are known to degrade caffeine, and yeasts and fungi used in food fermentation can lower caffeine during coffee fermentation while modulating flavour; ultrasound-assisted water extraction can remove caffeine in minutes. None is yet an industrial standard, so this entry records the direction of research rather than a commercial method.

Water use mediumSupercritical CO2 decaffeination

Supercritical carbon dioxide decaffeination uses CO2 under high pressure, where it behaves between a gas and a liquid, to dissolve caffeine selectively out of moistened green beans. The caffeine is then separated from the CO2, which is recycled. The method reaches 97 to 99 percent caffeine removal and leaves no organic solvent residue, but its pressure vessels and energy demand confine it to a few large industrial plants.

Water use highSwiss Water Process (water decaffeination)

The Swiss Water Process is a solvent-free decaffeination method operated at a single Canadian plant (and licensed elsewhere) in which caffeine is pulled from green beans by diffusion into a water extract already saturated with coffee solids, and then removed from that extract by carbon filtration. It is certified organic-compatible and widely used by specialty roasters. Peer-reviewed sources describe it as time-consuming and prone to some flavour degradation compared with newer methods. The company's own process page could not be fetched (rate-limited), so process numbers come from trade description.