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Making Exceptional Chocolate: Fermentation

Making Exceptional Chocolate: Fermentation

Talk about innovation in food!

It makes you wonder about those who initiated the process; navigating their gastric way from, essentially a nut filled with goo, to the sweet treat we know today was, truly, visionary. 

The process, one that relies on specific, carefully orchestrated chemical reactions throughout, looks to one reaction, in particular, to provide us with our delicious addiction.


Beyond the harvest and breaking open of the pods to expose the delicious insides – cacao and pulp – fermentation is really considered the first step in the actual production of cacao beans. 

Without fermentation, we could never have chocolate.

Fermentation is critical in producing quality, flavourful beans making for an exceptional final chocolate product. Fermenting the beans helps in developing the natural flavours of the bean, impacting significantly the quality of chocolate possible.

The process of fermentation breaks down the sugars and starches into acids or alcohol. It’s an important stage in the production of many types of food and drink, including coffee and alcohol.


To begin fermentation, the beans and pulp are immediately placed in large wooden boxes, otherwise known as “sweatboxes” or, in Spanish, “modulos”. 

These sweatboxes may be located at the plantation or they may be at the local co-op, where the beans are mixed with those from other local farms.

This occurs the same day as harvest. It's important fermentation is initiated as quickly as possible, as the beans begin to germinate as soon as the fruit has been picked. If germination is allowed to progress too far, the result is bitter beans, that cannot be improved with further processing. 

Filling the boxes is another opportunity for quality control. It is here that the producers are able to look for and identify any fungal infections that produce a deformity in the bean called witches' broom.

According to Scientific American, in 1988 it “reduced production by 80%.” It's not detectable in the harvesting but can be identified, and infected beans removed, as they are distributed into the fermentation boxes. 

Chemical Reactions Stimulate Flavour!

Chemical changes occur both inside and outside of the bean during this phase. The sweet pulp spurs the fermentation taking place on the exterior of the beans.

The fermentation, that begins once the boxes are filled the same day as picking, occurs as sugars start to get concentrated raising the temperature of the filled boxes. These temperatures can climb quickly to up to 58 °C [136.4°F], so hot that if you were to put your hand into the sticky gooey mass of beans, you couldn't keep it there very long.

As early as the next morning, the beans are stirred with plastic or wooden shovels, and transferred from one box to another, referred to as "turning". 

Fermentation Methods

The oldest method of fermentation, used through the beginning of the twentieth century, was to simply dig a small hole and place the beans in it. The beans were then covered with banana leaves to trap the heat generated by fermentation. The results were inconsistently fermented beans; and the mucilage coating liquefied and pooled instead of draining as it fermented, causing issues of quality.

The wooden canoe is another type of sweatbox method that dates back quite far and where the beans are stacked into what looks to be a wooden dugout canoe.

Unlike a canoe, however, there are small holes in the bottom through which the white mucilage coating can drain as the beans ferment. The cocoa beans are again covered with banana leaves to keep the heat inside the sweatbox and stirred periodically. There aren't many of these "canoes" remaining, and this method has is fast disappearing. 

An effective and thorough method of fermentation is achieved when the boxes are stacked in tiers, stepped like stairs, where one box can easily be tipped and poured into the lower – initiating a natural turning of the beans – and so on down the stack. This is one of the earliest “industrial” techniques.

Most often today, boxes of approximately four feet square and four feet tall and built from a wood that is conducive to fermentation – red cedar, in many cases.

Each box contains approximately one ton of beans. As with the stacked sweatboxes, holes in the bottom allow for aeration and drainage. The beans are shovelled from one box to the next with either wooden shovels or buckets. Long sticks are used to break up any clumps of beans and ensure that the beans are free flowing and are able to get plenty of air while they are fermenting.

In a common variation of this that often occurs at the co-op level, the boxes are fitted with steel frames. These allow for the boxes to be lifted into the air by an overhead hoist and then emptied into the next box. The dumping action breaks up the clumps of beans and allows fresh air to enter into the mix. The process of dumping one sweatbox into the next continues until the proper level of fermentation is reached.

Once turned, the beans are topped with banana leaves with absolutely no gaps for air to enter and left covered for 48 hours. Once that has passed, the beans are turned and covered once again, where the process repeats now every 24 hours or so for about a week.

While the fermentation is happening, the pulp will be dripping off the cacao beans. For this reason, the fermentation boxes have holes that the pulp can drip through, removing over 30% of the wet cacao weight.

It is on the second day of fermentation, with the ongoing generation of extreme heat, that the germ within the cacao bean dies. When the germ dies, important chemical changes begin as enzymes within the bean itself are released.

This is what is so important to the development of the chocolate flavour.  

When it comes to fermentation, consistency is key. There is an art and attention to detail that is fundamental to the process to ensure that these tons of beans aren't experiencing too much, or too little, fermentation.

Wild Mountain is so very fortunate to have sourced beans for each of our varieties that have mastered this process, providing us with superior beans that have been fermented to the utmost of standards and expertise.

The flavour of our chocolate is a testament to the quality of producers – farmers and co-ops – we rely on.