Processing Cocoa
Scientific Name: Theobroma cacao
Family: Malvaceae
Cocoa seeds ('beans') have
no chocolate flavour when fresh. In normal plantation practice, flavour
is produced by natural fermentation, usually in large (say 1 x 2 m x 1
m high) wooden boxes. The pods are broken, and the beans, with the
sweetish pulp surrounding them, decanted into the boxes.
The
mass soon begins to ferment, and a good deal of liquid drains away, in
the early stages, through holes of about 1 cm diameter in the bottom
boards.
After 2 days, the beans are turned out into another box,
to mix and aerate them, and this is repeated each day until
fermentation is finished, in 6-8 days. The beans are then turned out
and dried.
During fermentation, the temperature should rise to
about 50°C. Small amounts of beans will not heat sufficiently. The
smallest effective size for a box is about 60 x 60 cm, and about 1 m
high; this should be filled to at least 60 cm (about 90 kg of wet
beans).
As fermentation proceeds, the beans, which are purple
inside in the most familiar variety, become lighter in colour and
finally brown. In well-fermented cocoa, the seed-coat is loose, and the
cotyledons are easily broken into segments.
D.H. Urquhart, in
his book Cocoa (Longmans, 1955), describes artificial fermentation,
used to assess the flavour of small batches, single pods or even
individual beans. The pods were swabbed with an antiseptic, then opened
under aseptic conditions. Fermentation was started with a mixed
bacterial/yeast culture, or dispensed with; its only effect was as a
source of heat, and chocolate flavour could be produced by manipulating
the temperature in an incubator. Germination (or its early stage) was
found to be essential; dead beans, killed by heat or cold, would not
develop flavour.
Urquhart recommends a temperature of 35°C (not above 38 °) for the first 3 1/2 days, rising then to 50°C for another 3 days.
The
beans must be in a container of non-reactive material (not metal, but
glass, plastic, or un-chipped enamel) in a water-bath (e.g., a laundry
copper) for easier temperature control.
A false bottom must be
placed in the vessel, to allow separation of liquid, and the beans
stirred thoroughly every 24 hours (at least until 24 hours after the
rise to 50°C) to remove carbon dioxide.
Probably asepsis is not
vital. In the first few days the seeds are alive and can resist
infection; after the temperature rises to 50°C, most organisms will be
killed anyway.
I have had no personal experience of small-scale
fermentation of cocoa. It is to be hoped that someone may build a
method on the information given here, and pass on some more explicit
advice in the future.
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