How cacao is fermented and dried, and why it decides the flavor

Cacao is fermented by piling the fresh, pulp-covered beans in a heap or a wooden box for two to seven days. The beans are then dried in the sun until only about 7.5 percent of their weight is water. Fermentation and drying decide much of a bar's flavor before a chocolate maker ever sees the beans. The International Cocoa Organization (ICCO) gives about five days for Forastero beans and two to three for Criollo, and says drying takes the moisture from about 60 percent down to about 7.5.

How three well-known fermentaries work. All three buy wet beans from smallholders and ferment for six to seven days in boxes.

Fermentary	Where	Farmers it buys from	Fermentation	Drying
Öko-Caribe	Near San Francisco de Macorís, Dominican Republic	108, per Taza Chocolate's partner page	Six days in wooden boxes	About a week in the sun
Kokoa Kamili	Kilombero Valley, Tanzania	Buys only directly from farmers, at the farm gate and village buying stations	Six days in a three-tier cascade of boxes	Five to seven days on sun-drying tables, raked constantly
Maya Mountain Cacao	Toledo, Belize	411, per Dandelion Chocolate	Six to seven days in a line of boxes	Seven to 14 days on mesh decks in greenhouses

Why the beans have to ferment

A fresh cacao bean is bitter, astringent and full of purple pigment, and it tastes nothing like chocolate. Fermentation is what changes that. The beans come out of the pod coated in white pulp that is 10 to 15 percent sugar, and wild yeasts and bacteria start feeding on it as soon as the beans are piled. Nothing is added. A review by Luc De Vuyst and Stefan Weckx in the Journal of Applied Microbiology describes a careful spontaneous fermentation of about four days. In it, three groups of microbes follow one another, yeasts, lactic acid bacteria and acetic acid bacteria.

The yeasts go first, working on the sugars in the thick, airless pulp. As oxygen runs short, lactic acid bacteria take over. Then the pulp breaks down and drains away, air gets in, and acetic acid bacteria turn the yeasts' products into acetic acid, the acid in vinegar. A 2021 study in Scientific Reports by Calvo and colleagues follows the same sequence in Colombian fermentations.

What happens inside the bean

The heat and acid do their real work inside the seed. ICCO says the temperature of the mass climbs to 40 to 45 °C in the first 48 hours. The acetic acid soaks through the shell, and together with the heat it kills the germ, so the seed can no longer sprout. The Scientific Reports team explains that once the germ dies, the cell walls inside the bean break and enzymes start reacting with proteins, sugars and pigments. Those reactions make the building blocks of chocolate flavor that the roaster later brings out.

You can see it happen. The purple of a fresh bean fades as the pigments break down, and the inside of the bean opens into a cracked, ridged pattern. Farmers turn the mass every day or two, which ICCO says lets air in and speeds the bacteria up. Good fermentaries log the temperature and check each day's lot.

Heap or box

The two main methods are a heap and a box. In a heap, beans are piled on banana leaves and covered with more leaves to hold in the heat. In a box, beans go into wooden bins with slats or holes so the liquid can drain. Many fermentaries set the boxes in a cascade or a line, so the beans can be tipped from one box to the next each day to turn them. Kokoa Kamili's operations page describes a three-tier cascade, a partial overnight drain before the ferment starts, temperatures logged each day, and lots that miss the mark kept out of export.

Drying, the slow part

Drying stops the fermentation and gets the beans ready to store and ship. ICCO says it should be slow. Beans dried too fast stay acidic and bitter, and beans dried too slowly can grow mold and pick up off-flavors. It also says bean temperatures should stay under 65 °C. Fine cacao is often sun-dried on raised beds, tables, patios or greenhouse decks, and raked often so every bean dries evenly. ICCO notes that some farms use wood or fuel dryers, and smoke from a dryer can taint the beans.

Smoke is not the only way to get a smoky bean, though. Research from the Leibniz Institute for Food Systems Biology at the Technical University of Munich, reported in September 2026, found that overfermented beans can taste smoky, leathery and cheesy too. The cause is short-chain acids and smoky compounds that build up when fermentation runs too long.

Under, over and just right

Under-fermented beans make chocolate that is bitter and harshly astringent with little cocoa flavor. In the cut test they show up purple, or gray and dense, which the trade calls slaty. Over-fermented beans go very dark and can smell of ammonia or rot. The Scientific Reports study cites a working rule that a bean pH of 5.5 to 5.8 means fermentation is incomplete, and under 4.75 means the batch is over-fermented and very acidic. Its own target was about 5 to 5.2. Between the two is a narrow window, and hitting it batch after batch is a skill.

Why fermentaries buy wet beans

Most of the world's cacao comes from very small farms. About 70 percent of world production comes from West Africa, according to the ICCO. It adds that cocoa there is typically grown by smallholders and many farms have less than a hectare in cocoa. Fairtrade says about six million people depend on cocoa farming for their living. A family with a small plot may not have enough beans at once to fill a box and hold the heat, so each family's small batch ferments differently.

Fermentaries fix that by buying the beans wet, straight from the pod, and fermenting them together. Taza Chocolate's profile of Öko-Caribe describes farmers scooping fresh beans into buckets for collection. It says founders Gualberto Acebey Torrejon and Adriano de Jesus Rodriguez started the company in 2006 after meeting at a large organic cacao cooperative. Dandelion Chocolate writes that Maya Mountain Cacao was the first company in Belize to buy wet beans. Before it, farmers fermented in boxes of every size at home and dried on tarps or zinc roofing. The farmer gets paid sooner for less work, and the maker gets a lot that tastes the same from one sack to the next. It is also why many craft bars name the fermentary along with the country. To follow the beans onward, read what is inside a cacao pod and what bean-to-bar means, step by step.

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