Cocoa and Chocolate
Practical Action
Fermentation
Cocoa beans are fermented not just to remove the adhering pulp but also develop the distinctive
flavour of cocoa. Correct fermentation and drying of cocoa is of vital importance and no
subsequent processing of the bean will correct bad practice at this stage. A good flavour in the
final cocoa or chocolate is related closely to good fermentation but if the drying after
fermentation is delayed moulds will develop which will produce very unpleasant flavours.
After the pods are cut from the trees the beans with the adhering pulp are removed.
Fermentation is carried out in a variety of ways but all depend on heaping a quantity of fresh
beans with their pulp and allowing micro-organisms to ferment and to produce heat. Most beans
are fermented in heaps. Better results are obtained by the use of fermentation boxes which give
more even fermentation.
Fermentation takes five to six days. Forastero beans take rather longer to ferment than Criollo.
During the first day the adhering pulp becomes liquid and drains away. By the third day the
mass of beans will have fairly even heated to 45oC and will remain between this temperature and
about 50oC until fermentation is completed. It is necessary to occasionally stir the beans to
aerate and to ensure that the beans initially on the outside of the heap are exposed to
temperature conditions prevailing in the interior.
Drying
After fermentation the beans are placed in shallow trays to dry. In some growing areas where the
main harvest coincides with the dry season, sun drying is adequate. The beans are dried by
being spread out in the sun in layers a few centimetres thick. Sun drying trays may be movable
on rails so that they can be pushed under canopies. Where the weather is less sunny, artificial
driers are used. There are numerous types of dryers but an essential feature of all must be that
any smoky products of combustion do not come in contact with the beans otherwise taints will
appear in the final product. Some systems involve the complete combustion of the fuel so that
the flue gases can be used to dry the beans.
Cleaning
The beans are cleaned to remove the following extraneous matter: bean clusters and other large
pieces using rocking and vibratory sieves; light material like dust, loose shell and fibre using a
gentle upward air stream; iron particles using a magnetic separator and stones and heavy
material using a fluidised bed with air aspiration to lift the coca beans. It may also be necessary
to grade the coca beans according to size to ensure even roasting.
Roasting
This is the most important stage in the development of flavour. This can be achieved by roasting
the whole bean, the cocoa bean cotyledon or even the ground cocoa bean cotyledon (cocoa
mass). For chocolate production the roasting temperatures are 100C to 104C. For cocoa
powder production higher temperatures of 120 to 135C are used. There are many designs of
roasters: both batch and continuous systems. The operation is controlled so that: the nib is
heated to the required temperature without burning the shell or the cotyledon and producing
undesirable flavours; the heat is applied evenly over a long period of up to 90 minutes to
produce even roasting; the nib must not be contaminated with any combustion products from
the fuel used and provision must be made for the escape of any volatile acids, water vapour and
decomposition products of the nib. After roasting the beans are cooled quickly to prevent
scorching
Crushing
The shell will have been already loosened by the roasting. The beans are then lightly crushed
with the object of preserving large pieces of shell and nib and avoiding the creation of small
particles and dust. The older winnows used toothed rollers to break up the beans but modern
machines are fitted with impact rollers. These consist of two hexagonal rollers running in the
same direction that throw the beans against metal plates. The cocoa bean without its shell is
known as a “cocoa nib”. The valuable part of the cocoa bean is the nib, the outer shell being a
waste material of little value.
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