One of the most important steps in the long journey making chocolate from the bean is fermentation. And yet, it is perhaps the least understood and most capricious of all. 
Once the fruit of the cacao tree ripens, the football-shaped pods are opened and the pulp-covered seeds are scooped out and placed in wooden “sweatboxes” or other types of containers. The hot, humid air is a target-rich environment for all sorts of naturally occurring yeast and bacteria. Almost immediately, they begin converting the sugary pulp into liquid. Their hard work raises the temperature of the beans, stopping germination and beginning a series of chemical changes that have a big impact on flavor. Proper fermentation removes astringent tannins and other bitter compounds while adding body and richness to the finished chocolate that can’t be created later in the process. Yet this critically important step is often poorly understood by farmers and under appreciated by industrial chocolatiers.
In addition to setting up optimal flavor profiles, fermentation can unlock some of the unique characteristics that identify a particular place and bean variety known as “terroir”, the French term for “taste of place”. 
The type of microorganisms present during fermentation, in that particular place and that moment of time, is part of what gives beans their signature taste, just like wine. And, just like wine, the appropriate fermentation time varies with varietal and each harvest, running from 2-7 days. This is one of the reasons sourcing beans directly can make a huge difference. By educating farmers and encouraging careful fermentation, varying time and aerating the beans with just the right frequency, craft chocolatiers can nudge nature in the right direction to create a foundation of flavor that evolves throughout the rest of the process.
kim hack
Author