The Cocoa Fermentery
Preparing freshly-harvested cocoa ('wet bean') for sale has three stages which must be preformed within a few days:
Breaking
The beans inside the husk are individually enclosed in a thin membrane with a small quantity of sweet juice. Some harvesting is done year round, but the heaviest production occurs during the cooler months, April to August. In the plantation the beans are broken out of their pods into a bucket. This ‘wet’ bean is then carried in sacks to the processing site.
Fermenting
Removal of the slimy outer membrane is done by putting the beans, en masse, into a box (about one metre cube). Fermentation heats the mass which then needs regular stirring at least once a day to (a) stop them drying into solid lumps, (b) to encourage even processing throughout. This stage takes about a week depending on the bulk and the amount of attention given.
Drying
Once the self-generated heat diminishes drying needs to continue within a day or two or else a grey mould will form, spoiling the product. Spreading it out in the sun will prevent this but engenders risk of rain and contamination. Drying continues until the beans are hard and crunchy.
A high-volume Fermentary
For the owner-operator of an 8-tray solar drier who buys bulk ‘wet bean' from his/her neighbours, the greater capacity at the drier stage demands a matching increase of capacity at the fermentation stage. The solution, shown here, is taken from an early agriculture publication.
Though simple enough and hugely labour-saving it is now never found in village-based operations, probably because the cost and effort isn’t warranted when processing smaller amounts.
The original description shows stacking together 8-12 mesh-bottomed boxes filled with ‘wet’ cocoa. Each rack is filled in situ to about 100mm. A few sacks are then thrown over the top of the stack as extra insulation. Fermentation still takes about a week but does not need the constant stirring. Each rack must be emptied and removed again before the next lower one can be accessed.
Each rack holds the equivalent of one drier tray but needs to store the beans for about twice as long. Thus, if the solar drier is to be kept at full production there must be at least two stacks of fermenting racks in operation. The cost of the 25-30m. of cocoa-netting needed, on top of the 90-100m. of sawn timber, is quite prohibitive.
Improved design
Hence a cheaper, more robust and versatile alternative is suggested. This uses as many welded-pipe frames, as shown.
A copra sack when cut open is about 1.2 x 1.45m. This can be quickly hemmed over the frame on all four sides. Even when filled these ‘stretchers’ can be easily lifted and carried, with obvious operational advantages. No current costing is available: it is estimated to be about half of the timber and netting construct.
In operation some extra insulation will be needed to contain the heat within the stack. Copra sacks would be quite suitable for this.