Trust the (coffee) process.

You may not realise but coffee is a small cherry that normally house two coffee seeds (the beans). There's no major commercial use for the coffee cherry, so producers have to decide how to get it off the seed. That choice can dramatically shape the flavour and character of the coffee you end up drinking. Every producing region has its own quirks, but as a general rule there are three traditional processes for specialty arabica: washed, natural and honey. More recently producers have started experimenting with newer methods too, things like anoxic/anaerobic fermentation, carbonic maceration, cofermentation/infusion, and yeast or enzyme inoculation. For this blog we'll lump all of those under one banner: experimental.

Washed 

Fruit Removal: Typically within 24 hours of harvest with a mechanical de-pulper or de-mucilager.
Fermentation: De-pulped coffees can be held in fermentation tanks for 12–72 hours; de-mucilaged coffees are not usually held in tanks but moved to drying surfaces or equipment.
Drying Time: 18–36 hours mechanically; 7–15 days on patios, raised beds, or in parabolic dryers.
Profile: Clean, articulate flavours; caramel or sugary sweetness; wide spectrum of fruit acidity depending on other factors; capable of bright, crisp notes.

The quickest, and arguably most efficient, of the post harvest processing methods is often called the Washed or Wet process, though it doesn't always require much water at all these days. It's the primary method for preparing specialty quality coffee in most of Africa, Central and South America (except Brazil), and select parts of the Asia Pacific growing region.

The exact method producers use varies depending on the place, tradition, climate and access to fresh water, but "washed" typically means the coffee fruit has been removed from the coffee seed as quickly and cleanly as possible.

Fermentation begins the moment microorganisms such as yeast and bacteria start metabolising sugars, fructose and sucrose, in and around the coffee seeds. This can occur as early as the time of picking, when the fruit and stem are separated and a small hole is typically created in the coffee cherry. Fermentation still takes place in Washed coffees as long as there is either fruit material (mucilage) and/or a certain amount of water (11 percent moisture or greater) available as fuel.

What used to be left largely to ambient conditions, whatever the tank temperature happened to be, how humid the air was that week, is now something a lot of producers actively manage. Monitoring pH through fermentation and controlling temperature has gone from niche experimentation to fairly standard practice at quality focused washing stations. The line between "traditional washed" and what gets called "experimental" processing has blurred a fair bit as a result.

In the coffee industry we describe the length of fermentation as the period coffee is piled in tanks or held underwater, with the goal of either speeding up or slowing down the access microorganisms have to the fruit material. Open or dry fermentation describes coffees that are de-pulped and placed in open-air tanks or buckets to sit in their mucilage, typically for 24 hours or less though occasionally as long as 72. Underwater or wet fermentation can take longer, depending on the climate, water quality, and the population of microorganisms at play.

Water has always been the trade off with this process, and in the last few years it's become a much bigger conversation. A lot of traditional washed producing origins are not under water stress, so mills have been moving toward recirculating water systems, eco-pulpers, or different processing methods altogether.

Natural 

Fruit Removal: This is done after drying, and before being packed for export.
Fermentation: Occurs inside the fruit mucilage surrounding the seed and under the pulp, will take place as long as there is fuel available to the microorganisms (e.g. sugar, water, acids).
Drying Time: This process can take up to thirty days, weather permitting
Profile: Noticeably fruity or “boozy” flavours; can also have strong nutty and/or chocolate characteristics, and typically has a heavier or syrupy body.

Natural or "dry" process coffees are the opposite of washed. The fruit is picked when ripe and allowed to dry completely around the seed before being husked or hulled off. Historically hulling was done by hand with a mortar and pestle, today it's largely done by machine. Natural process coffees are most commonly found in Ethiopia, Yemen, Brazil, and Costa Rica, though producers around the world are also experimenting with this methodology. Zukuka Bora Coffee Company has built one of the more exciting naturally processed specialty Arabica programs to come out of Uganda, and it's now a well established part of their coffee program.

Fermentation occurs during the processing, from the moment the coffee is picked, possibly earlier. Local or intentional populations of yeast and bacteria enter the fruit and begin metabolising the sugars and acids inside it, a process that can continue until the coffee is dried. While the coffee itself isn't held in fermentation tanks, its fermentation is still very much shaped by the producer's choices, temperature, exposure to sun or shade, depth of the drying bed, and rotation schedule. What used to be described as things that "dictate" the outcome, largely out of the producer's hands, is increasingly something producers actively engineer. Raised beds with better airflow control, shade cloths, and more precise rotation schedules are now common at quality focused operations, aimed at getting a consistent, repeatable result rather than leaving it to whatever the season brings.

Drying natural coffees remains a considerably longer and riskier process than washed coffee, and that risk has grown. Naturals take up more space, require more attention and labour, and carry a higher risk of spoilage or over-fermentation, since the intact fruit material provides a long-term, concentrated fuel source for yeast and bacteria. On top of that, the same climate shifts making rainfall less predictable have made the drying window itself a bigger gamble, a well timed dry spell used to be reliable, now it's something producers have to plan around and hedge against with covered drying and more flexible infrastructure. Natural processing is the oldest technique for preparing coffee, and in ancient times, as well as in some cultures today, the fruit was left to dry completely on the branch and harvested only when needed. Modern natural coffees are harvested ripe and intentionally dried, typically on patios, raised beds, or drying tables, with more producers building in covered or mechanical backup options than would have been standard even five years ago.

Honey

Fruit Removal: Fruit skin is removed within 24 hours of harvest; all or some of the mucilage is left to dry on the seeds.
Fermentation: Occurs throughout the drying process, with the skin of the cherry removed to produce similar characteristics to Natural processed coffee.
Drying Time: Drying is anywhere from 18–25 days, and has less risk of spoilage than the Natural process.
Profile: Can express some fruity/boozy/jammy flavours or stewed-fruit-like characteristics; caramel or burnt-sugar sweetness; nuttiness.

Honey processing has emerged relatively recently as a processing style favoured by specialty coffee producers across the globe, and no, no actual honey is involved. This process is essentially identical to the traditionally Brazilian method known as Pulped Natural. It's also worth noting Honey uses meaningfully less water than washed processing, which has made it an increasingly appealing option in water stressed origins looking for a middle ground.

The skin of the coffee cherry is removed, and the seed is allowed to dry with some or all of its sticky fruit mucilage intact. This process retains some of the desirable characteristics of a full natural (heavy body, sweet fruitiness with lower acidity, deep chocolate notes) while speeding up the drying process and reducing some of the risk of spoilage, mould, and other defects that can occur with natural processing.

Honey process varies greatly depending on how much mucilage is left on the seed, and producers are getting more precise about controlling that rather than leaving it to chance. Yellow Honey removes the most mucilage, leading to milder characteristics; Red Honey sits in the middle; Black Honey leaves the majority of the mucilage intact, leading to a character closest to a fully natural coffee. The most obvious benefit to the Honey process over full naturals is the speed and efficiency of drying and the control over flavour characteristics. But the exposed fruit material also creates more risk for producers, since it requires more work to prevent taints from developing.

Often these coffees may also have an uneven or inconsistent appearance in their green form, which can be unappealing for roasters used to the more uniform look of washed coffee.

Experimental 

Fruit Removal: Not typically where the experimental step happens. Fruit removal will usually follow one of the traditional methods, washed, natural or honey, before or after the intentional fermentation step is applied.
Fermentation: Typically the variable being deliberately manipulated. Producers control oxygen exposure, temperature, added cultures, or co-ferments like fruit and spices to push flavour in a specific direction, well beyond what happens in a standard washed or natural process.
Drying Time: Also varies depending on the base method used, typically similar to whichever of washed, natural or honey the process is built on top of.
Profile: Highly variable and often intense. Can range from tropical fruit and wine like notes through to funky, spiced, or fermented flavours not usually found in traditional processing, depending on the specific method used.

Experimental processing isn't really one process, it's a catch all for anything where producers are deliberately intervening in fermentation to chase a specific flavour outcome, rather than working within the conventions of washed, natural or honey. Its growth over the last decade has been driven both by pure curiosity and, of course, by economics. Successful experimental lots can command a premium in the specialty market, and demand from roasters and consumers chasing new, unusual flavours has made experimental processing a potentially profitable opportunity for producers willing to take it on.

Anoxic or anaerobic fermentation removes oxygen from the equation, usually by depulping and then sealing the coffee in an airtight tank. Native yeast and bacteria consume whatever oxygen remains before anaerobic metabolism takes over, producing more intense, often fruitier or boozier characteristics than open air fermentation. It's one of the more widely adopted experimental methods, in large part due to its ease of use, and it's become common enough that many producers now treat it as a standard option rather than a novelty.

Carbonic maceration is a variation on anoxic/anaerobic and borrows its name from winemaking. Whole cherries go into a sealed tank that's then flushed with carbon dioxide, and because CO2 is heavier than air, it displaces oxygen almost immediately, rather than the slower, microbially driven oxygen depletion you get in standard anaerobic fermentation. That triggers enzymes inside the cherry itself to begin breaking down sugars. The result is often described as bright and wine like. Worth knowing that "carbonic maceration" gets used loosely on some listings without a formal industry standard behind the term, so it's not always clear the process was done exactly this way.

Cofermentation or infusion involves adding something else into the fermentation alongside the coffee, typically fruit, spices, or other organic material, to influence the flavour as it ferments. This is the most contentious of the experimental methods. It blurs the line between processing and flavouring, and there's an ongoing debate around disclosure, whether producers and roasters are being upfront that a coffee's fruit or spice notes come from something added during fermentation, rather than emerging naturally from the coffee itself.

Yeast or enzyme inoculation takes a more precise approach, introducing specific cultured strains into the fermentation tank to get a consistent, repeatable result. Rather than relying on whatever wild yeast and bacteria happen to be present, producers select strains known to produce particular characteristics.

Experimental processing comes with a degree of risk. These methods usually need specialised equipment (sealed tanks, one way valves, temperature control) and genuine expertise to achieve good, predictable results. A producer who jumps on the trend without that expertise or infrastructure can lose an entire lot if fermentation goes wrong, a bigger financial hit than a failed batch of washed or natural coffee, given the extra investment involved. There's also a market risk: experimental lots are often priced at a premium, but that premium depends on the market's appetite for the trend continuing, and on buyers trusting that what's on the label reflects what actually happened to the coffee.

As with washed, natural and honey, no two producers do experimental processing exactly the same way. It's still the least standardised of the four categories, but it's also where a lot of the most interesting and unusual coffees on the market right now are coming from.

Updated July 2026 from original 2019 blog