Cocoa Fermentation Sweatboxes

Overtime a number of different types of  cocoa fermentation boxes or “sweatboxes” have been used for cocoa fermentation. Thankfully, the techniques for building them continue to improve as do the techniques used to get a consistent fermentation.

Just a Hole in the Ground

One of the most traditional methods used up through the beginning of the 1900s to ferment the cocoa beans was simply to 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. Thankfully, this process is not used today to any great degree. The results were inconsistently fermented beans; and the mucilage coating liquefied and pooled instead of draining as it fermented, causing additional quality problems.

Wooden Canoe

Well, it isn’t a real canoe but it looks like one. With this type of sweatbox, the beans are stacked into what looks to be a wooden dugout canoe. Unlike a canoe, though, there are small holes in the bottom through which the white mucilage coating can drain as the beans ferment. The cocoa beans are covered with banana leaves or a similar coating to help keep the heat in. Periodically, the beans are stirred with long wooden stirring poles. Not many of these remain, and this method of fermentation is disappearing. It would not be surprising if this technique traced its way back to the Mayans or Olmecs.

Stacked Sweatboxes

antique stepped fermentation boxes.

Antique Stepped cocoa fermentation boxes.

One of the earliest “industrial” techniques of fermenting cacao is to build a set of boxes, each box set on top and to the side of the next, creating in effect a set of stairs. Holes in the bottom allow for drainage as well as air circulation. The fermenting starts with the beans being hauled up and emptied into the boxes on the top level. As the cocoa bean fermentation continues, the beans are removed from the bottom box and then dried. The beans in the next higher box are shoveled into the bottom box, this turned and aerated them. The process continues up to the top box where new beans are then added. This happens once or twice a day depending on what the fermenting requirements are.

Modern Sweatboxes

New modern cocoa fermentation boxes

New Fermentation Boxes

Today, boxes about four feet square and four feet tall are built out of a wood that is conducive to fermentation. (The wood of choice is red cedar.) 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 shoveled 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.

Fermentation Times

The amount of time that the beans are fermented depends heavily on the type of bean. Criollo beans need a shorter amount of fermentation than do Forestero beans. This has much to do with Criollo’s naturally milder flavor; not as much fermentation is needed to cut their harshness, compared to the harsher varieties of cacao. Fermentation times from five to seven days are typical.

When the fermentation is complete, the cocoa beans must be removed from the sweat boxes and carefully dried.

Consistency is a Virtue

No matter how the fermentation is performed, the key is consistency. The beans need to be fermented as perfectly as they can as well as be as consistently fermented as possible. While this task may seem easy, in fact it is very difficult. The farmers deal with literally tons of beans, and that makes stirring, fermenting, and processing consistently very difficult. It can be done, however. There are three classes of farms or co-ops. Some have poor quality beans but are able to ferment them well, some have good quality beans but are incapable of fermenting them in a suitable way. If a chocolate manufacturer is capable of finding a farm or co-op where the nexus of these come together such that they not only have good beans but also are capable of fermenting them in a way that does justice to these small jewels, then the chocolate manufacturer has truly found a prize from which great chocolate may be made.

Needless to say, at Amano Artisan Chocolate, we scour the world for the few places where these nexuses exist. They are few and far between, and we have to look very hard to find them, but we believe that the chocolate that comes from these few sources is well worth it.

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