Chof

Cacao fermentation

Almost every chocolate bar starts as beans left to ferment for about a week in their own pulp. Fermentation makes the raw material that roasting later turns into chocolate flavour. Without fermentation, a roasted bean stays bitter and astringent.

Maintained byFelipeIICCT Certified Chocolate Taster and Chocolate Awards judge

What is cacao fermentation?

Cacao fermentation, also called cocoa bean fermentation, is what happens to fresh cacao beans in their own sugary pulp after the pod is opened, usually over five to seven days. Yeasts, lactic acid bacteria and then acetic acid bacteria feed on the pulp in overlapping waves, the mass heats to 45 to 50 °C, the seed dies, and its own enzymes break proteins and sugar down into the amino acids and simple sugars that roasting turns into chocolate flavour.

The microbes belong to the families that raise bread, brew beer, sour sauerkraut and turn wine into vinegar. They feed on the sweet pulp around the bean, and their acid and heat do the rest. Left too long, the same mass starts to rot, which is where the ham and blue cheese in a bad bar usually come from.

Most of the world’s cocoa is grown on small West African farms, where the usual ferment is a heap under banana leaves. The bars on Chof that name a method mostly say a wooden box, for about six days. The method alone does not make a bar better, and most wrappers do not say how the beans were fermented.

Holding a bar? Scan it in the Chof app to see how its beans were fermented, where that is known. Scan it in Chof

Purple-seeded beans from one box ferment, cut open on days 0, 2, 4 and 6
  1. Day 0A living seed: purple and tight, in white pulp.
  2. Day 2The seed has died, and its membranes give way.
  3. Day 4Brown spreads in from the edge.
  4. Day 6Brown and open, ready to dry.

Who ferments the beans

Usually not the chocolate maker. A farmer opens the pods, and the wet beans are fermented on the farm, in a heap or a few boxes, or sold the same day to a cooperative, an estate or a central fermentary that ferments for many farms. The person running the fermentary decides when to turn the mass and when to stop, lot by lot, by temperature and cut test.

A maker buys the dried beans and chooses lots by cut test and a sample roast. Some ask for a protocol: Friis Holm sells Nicaraguan Chuno turned twice and turned three times, as two bars. A few makers grow and ferment their own cacao, as Fu Wan does in Pingtung, Taiwan. Where a bar below names its fermentary, the note says who ran the ferment.

  1. FarmPicks the ripe pods and opens them.
  2. Farm or fermentaryFerments the wet beans. Decides when to turn and when to stop.
  3. DryingFive to fourteen days in sun, a solar tunnel or a dryer.
  4. Cooperative or exporterGrades the dried beans by cut test and ships them.
  5. MakerChooses lots, roasts and makes the bar. Some ask for a protocol.

What happens during fermentation, day by day

A cacao pod holds 30 to 40 seeds in a white, sweet, sharply acidic pulp. Once the pod is open, yeasts and bacteria work through that pulp in overlapping waves, and each one changes the acidity, the heat or the air the next one gets. Their acid, alcohol and heat kill the seed around the second day, and only then can its own enzymes reach the proteins and sugars a living seed keeps apart. The drawing follows one box. A heap, a basket or a sack goes through the same waves at its own pace.

A week in a fermentation box

One box, from the day the pods are opened. The numbered lines mark what happens when.

In a typical box ferment the mass warms from about 27 °C to about 48 °C around day three and eases to about 41 °C by day seven. Yeasts lead in the first day, lactic acid bacteria grow alongside them to about day three, acetic acid bacteria follow from hour 36 to hour 120, and Bacillus and moulds take over after that. In the drawing the mass is turned at 48 and 96 hours. In one Nicaraguan box the pulp pH was 3.8 at the start and 4.6 at day six, and it reached 8.5 at day twelve in the half left in. The bean turns from purple to brown and then dark.

  1. Seed dies, day 2. Around 48 hours, heat and acid have killed the seed, and its own enzymes start work.
  2. Turned again, day 4. This box is turned at 48 hours and again at 96. Each turn lets air in, and the acetic acid bacteria pick up again.
  3. Cut test, day 6. Around day six a cut shows brown, open beans, and most boxes stop.
  4. Too long, day 12. Left in until day twelve, the pulp pH reached 8.5 and smoky, medicinal compounds built up.
Illustrative. The temperature follows the textbook shape of a box ferment (Schwan & Wheals 2004). The pH dots are three measurements from one 500 kg Nicaraguan box (Krause & Steinhaus 2026), joined by straight lines, and the last one comes from the half left in until day twelve. The dashed line at 42 °C is the ceiling many raw-food labels use. Real boxes overlap these phases and vary by farm.
The drawing as a table
TimeMass temperaturePulp pHMicrobes at workTurnedBean
Day 027 °C3.8Yeasts, Lactic acid bacteriaPurple
Day 134 °CYeasts, Lactic acid bacteriaPurple
Day 245 °CYeasts, Lactic acid bacteria, Acetic acid bacteriaYesPurple
Day 348 °CLactic acid bacteria, Acetic acid bacteriaPurple
Day 447 °CAcetic acid bacteriaYesPart brown
Day 545 °CAcetic acid bacteria, Bacillus and mouldsPart brown
Day 643 °C4.6Bacillus and mouldsBrown, open
Day 741 °CBacillus and mouldsBrown, open
Day 12Not drawn8.5Bacillus and mouldsDark

  1. Yeasts

    Hanseniaspora, Pichia, Saccharomyces. From hour 0, strongest in the first day.

    The pulp is acidic, sugary and nearly airless. Yeasts turn its sugars into ethanol and carbon dioxide, and their enzymes break the pulp down until it drains away as sweatings.

    If the ferment stopped here: Slaty or purple, astringent and bitter, with little for a roaster to work with.

  2. Lactic acid bacteria

    Limosilactobacillus fermentum, Lactiplantibacillus plantarum. Hours 0 to 72, busiest from 24 to 48.

    Present from the first hour and growing alongside the yeasts. They eat citric acid and sugar and make lactic acid, and the pulp slowly becomes less acidic. As it drains, air starts to reach the mass.

    If the ferment stopped here: Under-fermented: mostly purple, with harsh acidity and thin flavour.

  3. Acetic acid bacteria and heat

    Acetobacter pasteurianus, A. ghanensis, A. senegalensis. Hours 36 to 120.

    Turning lets air in. Acetic acid bacteria oxidise the ethanol to acetic acid, and the reaction heats the mass to 45 to 50 °C. Heat and acid soak into the seed and kill it, usually around day two or three, and the pH inside the bean falls from about 6.5 to between 4.5 and 5.

    If the ferment stopped here: Sharp and vinegary, with the first brown showing at the edge of a cut bean.

  4. Enzymes inside the dead seed

    The bean’s own enzymes. From about hour 48.

    Once the seed dies, its membranes give way and enzymes meet what they were kept apart from. Proteases cut storage proteins into peptides and free amino acids, invertase splits sucrose into glucose and fructose, and the purple anthocyanins break down and seep out. Once air reaches the mass, polyphenol oxidase starts turning the remaining polyphenols brown, and the browning carries on through drying.

    If the ferment stopped here: Well fermented: brown and open, with the acidity in balance and ready for the roaster.

Louis Pasteur called fermentation la vie sans l’air, life without air, and the first day in a cacao box is exactly that. The rest of the week is what happens when air is let back in.

Drying is the second half of the same process. Over five to fourteen days on sun decks, in solar tunnels or in a dryer, the beans drop from about 55% moisture to about 7%, acetic acid evaporates, and polyphenol oxidase browns what is left of the purple. Dry too fast and acid stays trapped in the bean. Dry too slowly and mould moves in.

Over-fermentation, under-fermentation and the cut test

Fermentaries judge a ferment by cutting a handful of wet beans each day towards the end. Brown spreading in from the edge and an open, cracked texture say it is nearly done. The cut test the trade means comes later, on dried beans: 300 are cut lengthwise and counted by colour. Brown and open is well fermented, purple is under-fermented and slaty grey never fermented. ISO 2451 caps the slaty and mouldy share by grade, and trade contracts use their own terms: Good Fermented allows at most 5% slaty beans, Fair Fermented 10%.

  • SlatyNever fermented.
  • PurpleUnder-fermented.
  • Part brownPartly fermented.
  • Brown, openWell fermented.
  • DarkOver-fermented, though some varieties dry this dark anyway.
  • Pale, openA well-fermented white Criollo bean.
Dried beans cut lengthwise, as a grader sees them.

The colour rule has exceptions. White-seeded Criollo beans carry little of the purple pigment, so they stay pale however well they ferment, and some varieties dry dark brown after an ordinary ferment. The drawings on this page follow a purple-seeded bean, the common case.

Mikkel Friis-Holm puts the right length at five to six days: too short and the bar stays bitter, too long and it drifts toward blue cheese. His Rugoso “Bad Fermentation” is the short end, made on purpose.

What too long does was measured in 2026. Krause and Steinhaus split two boxes, 500 kg in Nicaragua and 50 kg in Costa Rica, and left half of each in until day twelve and day nine. In the Nicaraguan box the pulp pH climbed from 4.6 to 8.5. Guaiacol tripled in one lot and rose tenfold in the other, and 4-ethylphenol went from about 2 to over 45 micrograms per kilo, against an odour threshold of 23. Those molecules smell of smoke, medicine and horse blanket.

The trade has long blamed smoky notes on beans dried over wood fires. A companion study by the same group confirmed that wood smoke leaves a near-identical set of molecules, with 2,6-dimethoxyphenol as the marker of smoke contact. The authors suggest tracking pH alongside the cut test to decide when to stop.

Rugoso, stopped early and fermented in full

Both bars are made from Rugoso, a cacao variety from Nicaragua. Friis Holm stopped its ferment early on purpose and says not all of the beans turned brown. ZOTO’s Rugoso had five days in a 1048 kg box, turned twice, to a profile ZOTO drew up for Ingemann in Nicaragua. The makers, roasts and cocoa percentages differ too, so the ferment is not the only variable.

Fermentation faults you can taste

A taste can point to a step in the process without proving it.

Flavour faults, the fermentation problem each can point to, and the other steps that cause them
Ham, blue cheese, sweatFrom the ferment: Usually a mass left too long.
Smoke, medicineFrom the ferment: Can be a mass left too long.Or from another step: Drying over a wood fire leaves near-identical molecules, and a cut test cannot tell the two apart.Mirzam Papua New Guinea 72%, dried over smouldering coals
Sharp, vinegary acidity with nothing behind itFrom the ferment: An early stop, or drying too fast.Or from another step: A light roast, a short conche, or the variety.
Astringency that grips after the sugar fadesFrom the ferment: Under-fermentation, which leaves more of the polyphenols in the bean.Or from another step: Washed cacao, on purpose.
Musty, mouldy, cardboardFrom the ferment: A very long ferment, once moulds take over.Or from another step: More often slow drying or damp storage.

Tasting one of these notes? Scan the bar in the Chof app to check how its beans were fermented, where that is known. Scan it in Chof

Cacao fermentation methods

Eight words turn up on wrappers, and they describe different things. Four name the vessel, two describe how the air and the microbes are steered, and two say something was added or nothing was done. Chof stores one method per bar, so a box ferment with a wine yeast is recorded as a box.

The vessel

Box, heap, tray and basket name what holds the beans. A bigger, better-insulated mass holds more heat.

  • Box fermentation

    Fermentation in slatted wooden boxes, from 50 kg micro-lots to boxes over a tonne, often stacked in tiers so the mass drops one level at each turn.

    A deep mass holds the heat, the slats let the sweatings drain, and each turn moves the beans and lets air in.

    Once the box is filled, turning and the day it stops are the main things a fermentary can still change.

    Length
    5 to 7 days, turned every 24 to 48 hours
    Named by
    433 published bars on Chof
    On Chof
    Bars include Friis Holm Chuno, Naive Las Trincheras, SOMA Mbingu and ZOTO Rugoso 75, whose box held 1048 kg.

  • Heap fermentation

    A pile of wet beans on banana leaves, covered with more leaves. The smallholder method behind most Ghanaian and Ivorian cocoa.

    The leaves hold the heat in. The edges cool faster than the core, so turning evens it out.

    Length
    5 to 6 days, turned every 48 hours
    Named by
    4 published bars on Chof
    On Chof
    Bars include ZOTO Manya 60%, a 277 kg heap turned three times. Bullion’s origins page, read in September 2026, lists its Ghana beans as heap-fermented under banana leaves.

  • Tray fermentation

    Shallow wooden trays about 10 cm deep, stacked so air reaches every layer without turning. Developed in Ghana in the 1960s.

    Thin layers let the air in on their own, so nobody has to turn the mass.

    Length
    4 to 5 days, no turning
    On Chof
    Trays turn up on wrappers mostly as drying surfaces.

  • Basket and sack fermentation

    Small lots fermented in baskets or jute sacks lined with leaves, usually by individual farmers before the beans are pooled.

    A small mass holds little heat, so it can stall before the acetic phase gets going.

    Length
    3 to 6 days
    On Chof
    Dandelion Gola Rainforest 70%, from leaf-lined baskets. Oialla Beniano 100%, from suspended baskets.

The air and the microbes

Anaerobic and starter describe how a ferment is steered: by keeping oxygen out, or by adding chosen strains.

  • Anaerobic fermentation

    Fermentation in a closed vessel, barrel or air-evacuated bag.

    With the oxygen kept out, the acetic acid bacteria have little to work with, so the yeast and lactic phases run longer.

    Mars filed a sealed-container application in 2014. It was published in 2015 and has since been abandoned.

    Length
    4 to 7 days, often without turning
    Named by
    5 published bars on Chof
    On Chof
    Bars include La Brigaderie Bonança 70%, and BAR Dark Idukki 60%, fermented two days closed and three open.

  • Starter culture

    Fermentation inoculated with chosen yeasts or bacteria, from wine yeast to laboratory strains, alongside or instead of the wild population.

    Added strains get a head start on the wild ones, and the aim is for one lot to ferment more like the next.

    Two yeasts added at the start raised free amino acids by 35.5% at 144 hours (Dias et al., in press). A nine-strain community reproduced fine-flavour attributes for a trained panel (Gopaulchan et al., 2025).

    Length
    4 to 6 days
    On Chof
    Bars include Fu Wan Alice and Taiwan #9, and Dandelion Camino Verde. Chof has no starter value, so these are recorded under their vessel or as other.

Something added, or nothing done

A co-ferment adds something to the mass. Washed cacao skips the ferment.

  • Co-fermentation

    Fermentation with fruit, spice, wood or leaves mixed into the mass.

    The added material ferments with the pulp, and the aim is for some of its aroma to reach the bean.

    In a 2007 trial in Bahia, Brazil, Amelonado beans fermented in bags of cupuaçu or soursop pulp tasted of the fruit in the nibs and the chocolate, which also had less cocoa flavour and more astringency than the control (Eskes et al., 2009).

    Length
    As long as the base ferment
    Named by
    7 published bars on Chof
    On Chof
    Bars include kamm Palo Santo. Ivee Promenade’s blackcurrant bar ferments dried beans a second time.

  • Washed cacao (lavado)

    Beans washed free of pulp and dried without fermenting. Lavado is the Mexican trade term.

    With the pulp gone there is nothing for the microbes to ferment, so the polyphenols stay in the bean.

    The Dominican Republic’s Sánchez grade is also unfermented, but dried with the pulp on.

    Length
    No fermentation
    Named by
    1 published bar on Chof
    On Chof
    Bars include ruvido Passatempo.

Some fermentaries also drain or remove part of the pulp before the box. ZOTO’s Ganzo from Peru went into a pre-drained 650 kg box for six days, and its Yunga from Ecuador into pre-drained crates for five. Kokoa Kamili lets its beans drain partly overnight. In a 2026 trial on an Amazon farm, the share of pulp removed and the time in the box both moved the acids.

Methods named by bars on Chof
  • Box: 95%
  • Co-ferment: 2%
  • Other: 2%
  • Anaerobic: 1%
  • Heap: 1%
  • Washed (lavado): under 1%

Among bars on Chof that name a method, with shares rounded. Chof has no separate value for basket or starter ferments.

Bars that say how they were fermented

Every bar on Chof has four fields for the ferment: method, length, turning and drying. They are filled from the wrapper, the maker’s reply and public pages such as the maker’s or a retailer’s website, and left blank when none of those says.

The note under a card is the maker’s or the fermentary’s own account. The line beneath it, where there is one, is the protocol as the Chof catalogue holds it.

Published bars on Chof, by what they disclose about the ferment
  • Say something about how the beans were fermented: 27%
  • State how many days: 9%median 6 days
  • State a turning schedule: 2%

Catalogue read .

Same beans, one more turn

Friis Holm makes two bars from Nicaraguan Chuno fermented for five days. The double-turned beans were turned at 48 and 72 hours, and the triple-turned beans were turned again at 96. Each turn lets air into the mass and restarts the acetic phase.

Same beans, dried at two speeds

Friis Holm dries one Madagascar lot two ways and sells both. The fast-dried beans got eight hours of sun a day from the first day. The slow-dried beans got two hours on the first day, four on the second and six on the third, then eight. Fast drying keeps more of the acetic acid in the bean.

One fermentary, many makers

Kokoa Kamili, in the Kilombero Valley in Tanzania, buys wet cacao and ferments it, and most of its customers are chocolate makers. By its own account the beans drain partly overnight, then spend six days in three-tier cascade boxes lined with banana leaves and rice bags, and five to seven days on drying tables. Svenska Kakao adds that the beans are turned on days three and five. Each maker below roasts the same fermentary’s beans to its own recipe.

Short and long ferments

Five to seven days is the usual range. Beans with little purple pigment and astringency, like many Criollo types, are often done in two or three. Qantu stops its Chuncho from Cusco at three days, and Original Beans its wild cacao from the Beni. Oialla ferments its wild Beniano beans, also from the Beni, in baskets for three days. Taman’s Mana beans from Davao, in the Philippines, get four. Amedei gives its Blanco de Criollo seven days, so a Criollo name does not promise a short ferment.

With air, and without

Closing the vessel keeps oxygen from the acetic acid bacteria, so the yeast and lactic phases run longer. Fazenda Bonança in Bahia ferments fully closed. The Idukki beans BAR uses spend two days closed and three days open, a protocol the maker confirmed to Chof in August 2026.

A chosen yeast

A wild ferment runs on whatever lives on the pod, the knife and the box. A starter adds chosen strains at the start. Fu Wan in Taiwan ferments with red wine yeast alongside the wild population, in a temperature-controlled room. At Camino Verde in Ecuador, Vicente Norero inoculates stacked bags with selected yeasts, and the aim is a ferment that runs alike from lot to lot. In a Brazilian trial, two yeasts added at the start raised free amino acids, the raw material of roast aroma, by about a third.

The whole protocol, printed

A few makers print the ferment the way a coffee roaster prints a process: mass, days, turns, drying. ZOTO in Belgium goes furthest and often gives the weight of the fermenting mass.

Co-ferments and a washed bean

Co-fermentation puts something else in the mass while the microbes work. kamm’s Palo Santo comes from cacao fermented with palo santo wood. Ivee Promenade, in Poland, gives dried Ugandan beans a second ferment with blackcurrant wine. ruvido’s Passatempo skips fermentation altogether. The Buzzz..ed Bar from BAR shows why the record matters. Its beans ferment for six ordinary days at Sadhu Farm near Mangalore, and the Maka di honey ale meets them only after drying, for two days. The wrapper calls it beer-fermented. It is beer-infused, a different step with a different effect.

Make bars? Add the fermentation method, days, turns and drying for each bar. A stated protocol counts toward the process part of the Chof Score.

Add your protocolHow the Chof Score works

How the beans were fermented

Method
Box, 1048 kg
Length
5 days
Turning
2 turns
Drying
7 days, open-air sun
Filled in from ZOTO Rugoso 75%.

Origin and process

The trees set the range. Genetics and growing conditions decide how much sugar and aroma the pulp holds and how much pigment and polyphenol the seeds carry, and the ferment and the drying decide where in that range a bean ends up. In a 2018 analysis, the pulp of CCN51, a high-yielding clone, had weaker floral and fruity aromas than the pulp of two other varieties. In a 2026 study, nibs from three farms in Far North Queensland grouped by farm on their aroma compounds, and the balance of lactic to acetic acid, a trace of the ferment, differed between farms. Each farm grew its own trees and fermented and dried its own way, so the study cannot say which of those made the difference. A single-origin claim tells you where the pods grew and little about who fermented them.

Coffee has been here before. Washed and natural are old words, honey processing spread from Costa Rica in the mid-2000s, and anaerobic took off after Saša Šestić won the 2015 World Barista Championship with a carbonic-maceration coffee. The Fermentation Project, a public cupping Lucia Solis and James Hoffmann have set for 3 October 2026, splits one Guatemalan lot four ways: no fermentation, and 48-hour ferments that are wild, Lactobacillus-led or Saccharomyces-led. A consumer almost never gets to taste that experiment with cacao. Friis Holm’s two Chuno bars are the nearest thing on a shelf.

Keep exploring

Cacao originsCacao varietiesConchingFine-flavour cacaoSingle-origin chocolateTypes of chocolateHow to choose chocolate

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Common questions about cacao fermentation

  • Is all chocolate fermented?

    Almost all of it, from supermarket milk chocolate to a single-estate 100%. The exception is washed or lavado cacao, dried without fermenting and used by a few makers for its astringent, tannic character.

  • How long does cacao fermentation take?

    Five to seven days for most cacao. Criollo-type beans with little purple pigment are often done in two or three days, and a mass left well past a week risks over-fermentation. Among the bars on Chof that state a duration, the median is 6 days.

  • What happens if cacao is not fermented?

    The bean stays slaty or purple, astringent and bitter, and it forms far fewer of the amino acids and simple sugars the roast needs. Chocolate made from it tastes flat and tannic. A few makers sell it on purpose as washed cacao.

  • Is raw cacao fermented?

    Usually, yes. "Raw" on a wrapper almost always means unroasted, and the beans were still fermented. A fermenting mass heats itself to 45 to 50 °C, above the 42 °C ceiling many raw-food labels use, a convention with no legal definition.

  • Which microbes ferment cacao?

    Yeasts such as Hanseniaspora, Pichia and Saccharomyces lead in the first day or two, with lactic acid bacteria growing alongside them from the start. Acetic acid bacteria, mainly Acetobacter, take over once air reaches the mass. In 2025 a defined community of nine strains reproduced the attributes of fine-flavour cocoa.

  • What does over-fermented cacao taste like?

    Hammy, cheesy, sweaty, smoky or medicinal. In a 2026 study, boxes left past day six built up guaiacol and 4-ethylphenol, the smoky and medicinal compounds, as the pulp pH climbed. Mikkel Friis-Holm puts it this way: too short and the bar stays bitter, too long and it drifts toward blue cheese.

  • What is co-fermented or double-fermented chocolate?

    Co-fermented means something else was in the mass while it fermented: fruit, spice, wood or leaves. Double-fermented means the beans went through a second fermentation cycle, and how that is done varies by producer. Both differ from an infusion, where dried beans or nibs are soaked in beer, a spirit or a barrel after the ferment.

  • What is the cut test?

    Dried beans are cut lengthwise, 300 at a time in the trade, and sorted by the colour inside. Brown and open is well fermented, purple is under-fermented and slaty grey never fermented. ISO 2451 caps the slaty and mouldy share by grade, and fermentaries also cut wet beans during the ferment to decide when to stop.

  • Does fermentation change how healthy chocolate is?

    It lowers the polyphenols that make raw cacao astringent. In a 2021 study, epicatechin, the main cacao flavanol, fell by half to three quarters over five days of fermentation, and drying and roasting take more. "Raw" and "fermented" are not reliable health labels on their own.

  • Does Chof reward makers who disclose their fermentation?

    Yes. A stated fermentation method, duration, turning schedule or drying method counts toward the process part of the Chof Score. Every named method earns the same credit, and fields a maker never disclosed stay blank.

    How the Chof Score worksAdd your protocol

Sources and further reading

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