Naming convention typically refers to this variable
What they call itPulp removalEnvironmentInoculants or additivesTime/contactGeneral descriptionAlso known as
WetYes, alwaysVariesIf you wantNot critical to definition/
varies wildly
"Wet process" is a general category that defines all coffee processes in which skin is removed before drying. It doesn't matter if there is never water used in the process—all we're talking about is whether the "wet" part of the cherry is exposed during drying. If the skin is removed at any point during processing, it's a wet process.
Dry aka naturalNo, neverVariesSometimesNot critical to definition/
varies wildly
"Dry process" is a general category that defines all coffee processes in which the coffee dries with the skin and pulp still attached. It doesn't matter if there is water used in the process either for floating or fermentation in cherry—all we're talking about is whether the coffee dries in cherry. Dry process is the opposite of wet process: if the skin stays on, it's a dry process.

"Natural" process is a synonym for this category, but it most commonly refers to coffees that have not undergone additional fermentation steps and is simply picked (possibly floated) and then dried in cherry.
Natural process
WashedYes, alwaysVariesSi lo quieresNot critical to definition/
varies wildly
Washed process refers simply to coffee that has had its mucilage removed. This can be done mechanically (in which case, it's most common for there to be little if any fermentation though it is possible to ferment both before and after mechanical washing and some producers do this) or via a fermentation to break down the pectin in the mucilage to allow the mucilage to be washed away by running water over the coffee. Every other variable in the equation is up for grabs—including fermentation in cherry and pre-ferments (and depending where you are, traditional practices vary wildly), but no matter what: the mucilage will be removed before drying.Fully washed
Pulped naturalYes, alwaysVariesSometimesUntil dryThis process evolved from the need to produce coffee faster and with lower risk of defects than the dry process method traditionally used in Brazil. The name is what it is: it's pulped (as in the skin is removed) but then it's dried like a natural (with the mucilage still attached).

This technique also describes honey processing (which comes in white/yellow/red/purple/black variants depending how much mucilage was removed) which is essentially the same thing. Popularized widely by Graciano Cruz in Panama around ~2010, honey processing aims to achieve different sensory profiles based on the amount of mucilage removed and a greater attention to cherry selection, with good honey processes achieving the body and sweetness that traditional coffee buyers would attribute to dry process coffee while also providing acidity and clarity more common to washed coffees.

Coffee that was pulped and then fermented can still be described as honey process—as long as it is dried with the mucilage still attached.
Carbonic macerationNo—at least not initiallyCarbon-dioxide flushedSometimesNot critical to definition/
varies wildly
Named after the winemaking practice common to the Beaujolais region of France in which whole grapes are fermented prior to crushing, this process was popularized by Saša Šestić during his WBC presentation in 2015. In carbonic maceration, whole coffee cherry is placed into a sealed vessel which is then flushed with carbon dioxide. If I'm being honest, this process not that dissimilar from "Anaerobic processing" in that both are intended to be low-oxygen environments—but in carbonic maceration the fermentation (the initial fermentation, anyway) must always happen in cherry, and carbon dioxide is always added to the environment.
AnaerobicSometimesLow oxygen / closed containerDoesn't matter/sometimesNot critical to definition/
varies wildly
This is one of those styles of processing that is all over the place in practice but refers pretty much exclusively only to one variable: the fermentation environment.

In most cases, producers will place coffee in a closed container (like a 55 gal drum) with an airlock, the idea being that as the fermentation progresses, oxygen in the tank is displaced by carbon dioxide produced through fermentation. Some producers go further and flush the fermentation environment with an inert gas like nitrogen, or carbon dioxide (see: Carbonic Maceration). The intention of this process is typically to advantage certain obligate anaerobes or facultative anaerobes (including yeasts such as Saccharomyces Cerevisiae or lactic acid bacteria) and disadvantage spoilage organisms like Acetobacter—as well as reducing oxidation. It seems logical enough.

But the situation often arises where temperatures aren't controlled well, or the fermentation progresses slowly and oxidation does occur and acetobacter does emerge as alcohol builds, pH drops, and the dormant bacteria find the oxygen...In reality, it's extremely difficult to actually purge all free oxygen from the environment even if you flush it with gas.

Besides: technically "Anaerobic" is a nonsensical fermentation style, since all fermentation is by definition anaerobic (if you listen to Lucia's podcast you know all about this by now)—but rather than referring to the fermentation, most producers are referring to the environment, which leads to a different term: the nearer-to-correct "anoxic" (meaning "without oxygen").

The situation gets more confusing when you realize that the "anaerobic" part of the process can happen in cherry, too—which may then be either dried, or pulped for a wet process; or it may occur after pulping as parchment. Without knowing more about what happened during the processing, the term "anaerobic" on its own is rendered unspecific and incomplete to describe a coffee.
Anoxic, hypoxic, sprouting
AerobicNot critical to definition/
varies wildly
(ambient air)
Not critical to definition/
varies wildly
Not critical to definition/
varies wildly
"Aerobic" being the opposite of "anaerobic" should get you pretty far—all that "aerobic" means is that the fermentation occurred in the presence of oxygen. This one is so close to acetic that I almost put it under the AKA column there if not for the specific references for that style. Most often I've seen natural processes from Brazil referred to as "aerobic" but it really can apply to any process—washed, natural, or honey—as long as it happens in ambient air in the presence of oxygen.
Acetic processDepends who you askOxygen-rich
(ambient air)
Not usuallyNot critical to definition/
varies wildly
This is another process that changes depending who you ask—but one thing that will always be true is that it requires an oxygen-rich environment as Acetic Acid Bacteria (AAB) are obligate aerobes (meaning that they require oxygen for their metabolism). Typically, acetic acid in coffee is thought of as a cause of the defect formerly known as "ferment"—which tastes like compost bin juice, overly sour kombucha, salad dressing, or rotting cherry (or to some, inexplicably: vanilla). However, in low concentrations, we perceive acetic acid (which is also generated during roasting) as fruity or floral (in fact, there is research using acetic acid as a way to improve the sensory character of coffee).

To La Palma y El Tucán, who popularized the "acetic process" naming convention, this process involves placing pulped coffee in a vessel where it can be mixed continuously during fermentation, exposing the coffee to oxygen and encouraging the growth of aerobic bacteria such as AAB (as well as yeasts like Saccharomyces Cerevisiae, which is most commonly thought of as a facultative anaerobe that is more efficient at replication in aerobic conditions). To other producers, this process means placing whole cherry under water in an open tank, which is mixed periodically again to encourage the growth of AAB.
Kopi LuwakYesI'll sayNoIt takes how long it takes ¯\_(ツ)_/¯ “Coffee from assholes, for assholes” (thanks, Jason). In this process, a civets cat eats (read: is usually captured, caged and force-fed) coffee. The "Processing" occurs when the seed passes through the digestive tract of the animal, fermenting the pulp and changing the coffee along the way prior to its.....departure...from the animal's body. Kopi Luwak coffee is weirdly heavy in body, low in acidity, and in so many words tastes like shit. It gives a different meaning to “Tail to snout." A similar process in Brazil called "Jacu" is named after Jacu (an African Grey Parrot), which eats and gastrointestinally ferments coffee cherry.This is another process that changes depending who you ask—but one thing that will always be true is that it requires an oxygen-rich environment as Acetic Acid Bacteria (AAB) are obligate aerobes (meaning that they require oxygen for their metabolism). Typically, acetic acid in coffee is thought of as a cause of the defect formerly known as "ferment"—which tastes like compost bin juice, overly sour kombucha, salad dressing, or rotting cherry (or to some, inexplicably: vanilla). However, in low concentrations, we perceive acetic acid (which is also generated during roasting) as fruity or floral (in fact, there is research using acetic acid as a way to improve the sensory character of coffee).

To La Palma y El Tucán, who popularized the "acetic process" naming convention, this process involves placing pulped coffee in a vessel where it can be mixed continuously during fermentation, exposing the coffee to oxygen and encouraging the growth of aerobic bacteria such as AAB (as well as yeasts like Saccharomyces Cerevisiae, which is most commonly thought of as a facultative anaerobe that is more efficient at replication in aerobic conditions). To other producers, this process means placing whole cherry under water in an open tank, which is mixed periodically again to encourage the growth of AAB.
CryomacerationYesVery cold waterSometimes yeastDays. Typically 200+ hours, but I've seen as many as 700+ (and Ben Morrow from Manhattan shared with me a sample of a coffee that was kept for some 9+ months)Cryomaceration seems—like carbonic maceration—to reference a winemaking technique bearing a similar name. The first time I ever tasted this process it came from Luiz Saldanha Rodriguez at Fazenda California in Brazil, where he developed what he called his "Cold Soul" process, which is a form of cryomaceration. Though there are of course variations, all follow some standard formula of placing whole ripe cherry in a closed container filled with very cold water (8-10º) where it is allowed to ferment—often for days or weeks—before being dried in cherry.

I've seen producers in Palestina, Colombia ferment pulped coffee under 10º water for 160 hours (as they've found it improves the "tail of the devil" flavor common to the selection of Castillo prevalent in their region), but to my knowledge, none of them refer to the process as "cryomaceration."
Cold Soul
Thermal shockYesVery hot and then very coldSometimes—usuallyDaysThis process—like a couple on this list—is best attributed to Diego Samuel Bermudez. While Diego very commonly will ferment cherry in low-oxygen environments (see: "Anerobic") prior to pulping, and then ferment coffee underwater at precise temperatures after inoculating with yeast (see: "Yeast") or other cultures, what sets Thermal Shock apart is the washing process: after fermentation, coffee is washed first with hot water (at 40º) and then cooled rapidly by washing it again with water at 12º. It's like the hot tub-to-pool spa ritual—but for coffee.
Tree-driedNoA treeNoUntil it's doneIt's as simple as it gets—and probably the only process that should actually be called "natural." Coffee is allowed to ripen and then dry on the tree. That's it. There are many risks, there aren't quality benefits, but it is what it is.Raisin
Thermal Stroke / thermophilic (NoVery hot – 75ºCNot usuallyMany daysThis is a weird one—with references and head-nods to hydro-natural-honey processing's partial dehydration, a low-oxygen environment, and the extreme temperature play of "thermal shock" coffee—but in reverse. In this process, whole cherry is fermented in a closed container low-oxygen environment for about two days, then partially mechanically dried/dehydrated (which in theory should inhibit bacterial activity) at temperatures not exceeding 35º. After that, it's placed back into that low-oxygen barrel and fermented at 70ºC for almost a day (!!) before completing drying on patios.
Bio innovationYes, eventuallyLow-oxygenA culture grown from wild microflora fed bits and pieces of each of the lots processed that year100 hours total (84 in cherry and 16 pulped)Like some others on this list, this process was introduced and marketed by La Palma y el Tucán. This one takes the prize for most ridiculous name—not only does it indicate nothing about the process itself, but it presents with great confidence and poise something that is not exactly new to coffee (in fact it's similar or related to a couple other processes I've described such as the "molecular" process). In this proprietary process, La Palma begins its fermentation in cherry inside of sealed, clay pots (a low-oxygen environment) for around 84 hours. LPET describes the clay as capturing the native yeasts—which then grow into a culture and continue to live inside the porous material through the harvest, meaning that the population should grow in strength and stabilize in population over the course of the harvest as the charge increases. To the delight of many competitors and high-end specialty buyers, it also means no two lots will be identical. After this extended cherry fermentation, the coffee is pulped and washed using the traditional method.

It reminds me of the cheesemaking nun from episode 4 of the Netflix documentary series Cooked, but also of one other thing: In places like Costa Rica, Kenya and other regions with concerns about water usage, recycling water at various stages of the process—whether for floating cherry, pulping coffee, or even fermenting or washing coffee (!) has become common practice. This means that at the beginning of the harvest, the water may be crystal clear but by the end it will be dark, turbid and charged with microbial life—kind of like a less-controlled inspiration for the so-called bioinnovation process. Similarly, in many places around the world where fermentation happens in unsealed concrete tanks, the biological charge will build over the course of the harvest to the extent that the tanks will smell of microbes by peak harvest and have visible microbial growth. UPDATE: Dakota Graff has helpfully informed me that LPET has moved away from using clay pots because they're unnecessary owing to the inoculate. True, but—for shame. The romance!
High GravityDoesn't matterVacuumSelected yeastTypically fasterBased on research from the brewing industry, this type of experimental fermentation happens under vacuum. By pumping out air to create a vacuum in the headspace of a steel fermentation vessel (rather than flushing it with a gas like carbon dioxide), fermentation can be accelerated with the added benefit of homogenizing moisture and fermentation metabolites in the coffee pile.
IPA AnaerobicYes, eventuallyLow oxygen / closed container (twice)Yes, IPA yeast and hops (after pulping)~120 hours in cherry,
~96 hours after pulping
In the US craft beer scene, the sour beer craze followed an IPA craze. In coffee, perhaps, we went from sour coffee of the early 2010s to now reaching back into our nostalgia for bitter tropicals—or that's my mental picture of how this process came about. This process starts with a 120-hour, low-oxygen cherry fermentation. After depulping, the coffee is again fermented in a low oxygen environment for 96 hours but this time with yeast selected to ferment Imperial Pale Ale style beer and hops added. Hops contain high levels of terpenes which act to stave off spoilage organisms and scent the coffee with the bitter, tropical character typical of this processing style.
Yeast processingSometimesNot critical to definition/
varies wildly
Yes, at least yeastNot critical to definition/
varies wildly
I've noted in past entries that this method has existed in some form for literally 70 years, but in short: in yeast processing, somewhere along the way—as cherry, as pulped coffee, even post-washing ahead of drying—yeast is added to the coffee at a tremendous ratio to crowd out competing microorganisms and spoilage organisms and select for a certain strain, giving a producer control over the process and the end result. Typically, producers will use a selection of Saccharomyces Cerevisiae selected from wine making catalogs (like from Lallemand or Laffort—or Lalcafe, which is a selection of wine yeasts from Lallemand's catalog that have been tested and proven for use in coffee) but using yeasts from beer making is common, too (although I can't advise it unless you like swampy, cheesy, sweaty coffee).Inoculated fermentation
Yeast controlled fermentation
Koji processingSometimesTemperature varies;
must be an oxygen-rich
environment during koji
growth until fruiting
Yes, at minimum kojiNot critical to definition/
varies wildly
If you haven't read my post on koji processing—start there. It's where all of this nonsense began. In koji processing, spores of a mold (known as koji) as sprinkled on the coffee—either cherry or parchment (typically cherry)—and allowed to grow. The metabolism of koji produces enzymes that increase the perception of body by generating amino acids (this done by protease, primarily) as well as break down starches (amylase enzyme), producing fermentable sugars available to other microorganisms for secondary, sequential fermentation. In other words, is a "pre-ferment" fermentation. Like with yeast, is possible to use koji at nearly any stage of processing, but it's most common to apply koji to cherry.Koji supernatural
Lactic processOftenLow-oxgyen, sometimes a 2% salt solutionSometimes a starter culture
Sometimes salt
Not critical to definition/
varies wildly
La Palma y El Tucan famously introduced this process—or at least named it.

Put simply, the goal of this process is to advantage Lactic Acid Bacteria (LAB) and disadvantage other types of bacteria and yeast. There are several ways to go about this, the most common of which is to inoculate the tank with a starter culture (not actually bacteria, for reasons Lucia describes here) often made from fermenting cascara or whole cherries (sometimes with salt added)—but sometimes created using non-coffee fermentation media as well. This method works like sourdough—essentially building a colony of microorganisms that is pitched into the tank to kick start fermentation. Additionally, these fermentations are most often conducted in low oxygen environments, as LAB tend to dominate in anaerobic, acidic environments rich with carbohydrates.

One of the more interesting variations I've seen recently—first from José Jadir Losada at El Mirador in Huila and then again from Lucia, is to use a 2% salt solution to control the fermentation. This is a traditional formula for lactofermentation, of course, as many types of LAB are either halotolerant or halophilic—and seems to produce clean, repeatable results with inexpensive inputs (it reminds me of a producer in Hawaii that floats their cherry with salt water. This was the first time I ever experienced the cognitive dissonance of coffee not tasting like I thought it should. I expected it to taste salty: it didn't).
Salt process
MolecularUsuallyDoesn't matter but in practice usually a closed containerA culture typically
grown from coffee cherry
Not critical to definition/
varies wildly
This is a newer process that I've seen coming from India. From the outside, it looks very similar to styles of processing like anaerobic or lactic—coffee in a closed container with an airlock on top (in fact I almost dropped it under the "also known as" for lactic process). What makes this style different, though, is that it specifically and always refers to coffee that has been inoculated with a starter culture cultivated from coffee cherry from that specific farm. The idea here is that you'd somehow amplify and control the native microbes found at one farm—creating consistency through the harvest and, depending on the environmental conditions in which that culture was grown (oxygen availability, sugar availability, salt, temperature) selected for certain attributes. Most commonly this coffee is pulped and processed as a wet process.Very similar to Bio-Innovation
Cascara tea processYes, alwaysVariesCascara — either as dried cascara, fresh pulp, or even freeze-dried cascara, cascara tea, or frozen cascara tea (looking at you, Aida)Not critical to definition/
varies wildly
Unless you're Luca—this process typically refers to a style popularized by Aida Batlle where parchment coffee ferments in tea made from coffee skin (or, alternatively, adds frozen chunks of cascara tea to the fermentation. That method helps a lot to combat the 30ºC daytime temperatures in Santa Ana. Or, back in 2017, I tasted a coffee with Aida that she'd processed using freeze-dried cascara tea).

Often, lower-quality coffees and hybrids will macerate in tea made from the skin of higher grades (like red bourbon, SL28, etc.). This method tends to add a slight red fruit character and complex acidity to coffee when executed well.
Kombucha processYesVariesA SCOBYNot critical to definition/
varies wildly
I've only seen this process a few times (once this year from Unblended Coffee out of Colombia), but the distinctive part of this process is that rather than inoculating the fermentation with commercial yeast or a starter culture made from cherry, it's inoculated with a SCOBY ("symbiotic culture of bacteria and yeast") typically used for producing kombucha. Most SCOBYs that I'm aware of contain high levels of LAB and AAB as well as yeasts like Schizosaccharomyces pombe, Brettanomyces bruxellensis, Saccharomyces cerevisiae, and Zygosaccharomyces rouxii (Villarreal-Soto et al., 2018). In other words—while the population may differ between a SCOBY and a spontaneous coffee fermentation, they contain many of the same species, allowing the Kombucha process to have a jump start in fermentation.
Yogurt processYesVariesYes, a yogurt cultureNot critical to definition/
varies wildly
This is related to the Lactic process, in many ways, as well as the Kombucha process—almost so much so that it's not worth mentioning as a separate process except that it specifically refers to coffee that was inoculated with yogurt starter cultures to kickstart fermentation and attempt to select for those specific LAB—all of which may have different sensory characteristics and require different environmental conditions (think of the "yogurt" setting on your Instant Pot, here)
Flower culturedYesAmbient, exposedYes, a starter cultured from coffee blossoms3 day fermentationMost of the time, when producers use a starter culture grown from material on their farm, the microbial population is not known. In the case of flower-cultured coffee, however, the producer that developed the process (Aquiares in Costa Rica) identified the yeast growing on freshly-opened coffee blossom (Metschnikowia pulcherrima and Hanseniaspora genus yeasts—both of which also grow on wine grapes), and then, they say—cultured them on agar. Once this culture was established, they used it to inoculate coffee at 5% concentration with water and pulped coffee, allowing the fermentation to progress for three days before drying the coffee.
[Color]-washedYesNot critical to definition/
varies wildly
The juice and/or pulp of a coffeeNot critical to definition/
varies wildly
A variation on washed coffees that does a lot of things, "orange" washed coffee is essentially "washing" pulped coffee with macerated cherry juice and pulp and "golden" washed is the same—but sans the pulp.

This one is related to cascara processes in its use of coffee pulp in the process.

Using water in processing has ecological disadvantages, and also may reduce flavor intensity as many of the compounds produced during fermentation and some inherent to the seed are water-soluble (therefore—at least in theory—by washing coffee we're essentially diluting the strength of the coffee). By washing the coffee with its own juices and pulp, producers are attempting to preserve the flavor intensity while also adding additional sugars and microbial charge (which will accelerate or at least change the fermentation).
Natural-hydro-honeyYes, always, eventuallyVariesWater..... sort ofThe process requires "interruptions"I first saw this process from Elkin Guzman at El Mirador in Pitalito, Colombia—but since it's a relatively simple process to execute it's been replicated widely. This process is interesting in how it manipulates hydration as a way to select for certain fermentation kinetics. To start, cherry is partially dried (the "natural" part of the process), which allows for the red-fruit dominant notes from dry processes to set in. At this point, the coffee would be too small or dry to pass through a pulper, so it is then rehydrated in water ("hydro") for something like 36 hours and then pulped. After pulping, it is dried on raised beds with mucilage still attached ("honey"). This process tends to produce coffee that has fruit character typical of dry process coffees but with sweet-tart characteristics more typical of honeys.
Wet hulled / giling basahYes, alwaysUsually ambientRarelyVaries, but not dried fully prior to hulling"Giling basah" is the Indonesian term for this process commonly practised in Indonesia—and literally translates to "wet grinding." It is very much a product of the challenges of transporting coffee from a smallholder's coffee garden to a central mill or purchasing point. The wet hulled process starts off very similar to a washed coffee (and is called "semi-washed" for a reason)—coffee is picked and then pulped. At this point, the pulped coffee is placed in bags (usually made of jute) for up to a day—this is typically when it would be brought to the central collection point. After that, the coffee is washed of mucilage, and laid to dry. Unlike in most methods where coffee is dried to less than 13% prior to removing the husk, wet hulled coffee is dried to just about 30% and then milled. The very high moisture coffee (which was hulled wet..... get it?) is then laid out to dry as green coffee to its final moisture content for export.Semi-washed
MonsoonedNoMonsoon conditionsNoMonths of contact with monsoon conditionsSo — I thought about not listing this one since technically it's not a primary postharvest process but occurs after coffee has already been dried—but since it's unique to coffee processing in that it's a legally protected process (under India's Geographical Indications of Goods Act) it's worth a mention (my own interest in rehydrating coffee aside). In the Monsooned process, coffee is dried in cherry then stored until the onset of monsoon season, at which point they are kept in ventilated warehouses for the entirety of the monsoon season (3-4 months) and subjected to the wet wind. This causes the coffee to swell up and pale in color—almost looking like parchment coffee. The process is supposed to simulate the conditions that coffee might have experienced during the British colonial period, when coffee was shipped in wooden barrels via ship—through monsoons and months' long journeys. I guess you can think of Sumatran barrel aged coffee similar in its intention, in that regard—but while I do favor whiskey processed overtime and subjected to seasonality, I can't say the same of this coffee which is characteristically earthy, musty, nutty and chocolate with very little acidity.related: Sumatran barrel aged coffee
Deconstructed FermentationYes, eventuallyThe pulp and juice are fermented separately from the coffee, then reunited later. and then the coffee is washed with very hot and then very cold waterA culture grown from bits and pieces of coffees that was inoculated with a selected strain of yeast cultured and grown in coffee juiceVery long... days... weeks...This is the process that kicked off the now-infamous "adulterated coffee" controversy and which members of the Espresso Aficionados Discord server refer to, in a tongue-in-cheek manner, as "illegal coffee." It combines almost every other process on this list in some way—carbon dioxide flushing, low oxygen fermentation, swabbing and culturing specific strains of yeast, growing a culture from bits and pieces of coffees inoculated with that one strain, back slopping the the fermentation, and thermal shocking. This is basically like the final exam in calculus when the teacher has been telling you all semester, "everything is cumulative."

Diego Samuel Bermudez developed this highly sophisticated protocol. The flavor outcomes depend on the inputs, timing, and selection of microorganisms, but I've provided a generalized overview here (I highly recommend Barista Hustle's post on the process).

Essentially, ripe (or overripe) cherry is washed with oxygenated water (to knock back spoilage microbes) then fermented in steel bioreactors flushed with carbon dioxide. As the cherry breaks down and juices are released, those juices are collected. Diego and his team then select a strain of yeast they've cataloged and grown into a culture on agar and add it to the separated cherry juice (Each of the strains is selected for a specific, known sensory outcome which is partly why many of Diego's coffees taste so loudly of one type of fruit or flavor). This inoculated juice is then used to ferment mucilage and pulp (collected from many lots) in a second bioreactor to prepare the culture for the final fermentation phase. When the culture is ready, coffee from the first bioreactor is pulped and the seeds, mucilage and culture from the second bioreactor are fermented together in a new bioreactor. That final fermentation is allowed to progress as long as needed—often 4-5 days. Finally, the coffee is washed using Diego's Thermal Shock technique.