Pre-harvest | Post harvest | Fermentation | Storage | Shipping | Standards
Drying
At the end of fermentation, the moisture content of the whole bean is approximately 60%, and this must be reduced to 7 – 7.5% before the cocoa can be stored, sold or transported. If the moisture is reduced too much, the shells become too brittle and break. If moisture is too high, mould growth occurs during storage.
The rate of drying is critical to final quality. Too rapid a drying rate results in excessively acid beans with case hardening (shriveling).
Sun Drying
Sun drying is carried out on wooden floors in “cocoa houses”, artificial dryers can be used or a combination of sun and artificial drying.
For sun drying, freshly fermented beans are spread on the floor of a cocoa house each day to a depth of not less than 5 cm and mixed regularly by walking through the layer of beans making small ridges and furrows.
At the start of the crop season when there is more residual mucilage around the bean after fermentation, the beans are banked in two long rows in the centre of the floor for the first night to complete the fermentation process and spread out on the floor of the cocoa house the next morning for further drying.
Artificial Drying
Artificial drying is commonly used after sun drying has reduced the moisture content to approximately 20%. A large mechanical dryer usually comprises a diesel burner with a blower. This blows hot air through a plenum onto the base of a wooden drying bed. The hot air passes through 8 mm holes drilled in the wooden floor through an 8-10 cm layer thickness of cocoa beans. The beans are spread out on the floor to a depth of not less than 5 cm and turned regularly with wooden rakes or paddles to ensure even drying.
Typically, artificial dryers in Trinidad and Tobago do not have heat exchangers to prevent contamination by direct contact with smoke in the heated air from the diesel burners. This makes it essential to service diesel burners regularly to prevent smoke and diesel fume contamination. Even though well maintained diesel burners may not contaminate beans with smoke, there is still a risk, and the installation of heat exchangers to remove this risk of smoke contamination should be considered.
In an alternative design, the dryers may comprise 6 arms which radiate from the centre of the dryer fixed to an annular ring which functions as a large cog, the stirring mechanism is driven from the edge. The arms carry strips of wood inclined downwards to facilitate stirring. Hot air is directed into the drying chamber from under the platform through holes drilled at the base of the circular platform.
Polishing
During drying the beans are polished to improve their appearance. The beans are polished at a stage where they are hard but not brittle in a rotary type dryer described above or a special polishing machine similar to a grain mixer. Polishing improves external appearance of the beans and it is suggested that polishing protect the beans from fungal infestation during storage.
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