Cocoa beans are dried after fermentation in order to reduce the moisture content from about 60% to about 7.5%. Drying must be carried out carefully to ensure that off-flavours are not developed.
Drying should take place slowly. If the beans are dried too quickly some of the chemical reactions started in the fermentation process are not allowed to complete their work and the beans are acidic with a bitter flavour. However, if the drying is too slow, moulds and off-flavours can develop. Various research studies indicate that bean temperatures during drying should not exceed 65oC.
There are two methods for drying beans - sun drying and artificial drying.
For sun drying, the beans are spread out on mats, trays or on concrete floors in the sun. In some countries in the West Indies and South America drying takes place on wooden drying floors with moveable roofs. The beans are normally turned or raked to ensure uniformity of drying and the beans need to be covered when it rains. Sun drying is used in countries where harvesting occurs in a dry period such as West Africa or the West Indies. With adequate sunshine and little rainfall, sun drying may take about one week, but if the weather is dull or rainy it will take longer.
Artificial drying may be resorted to in countries where there is a lack of pronounced dry periods after harvesting and fermentation, such as Brazil, Ecuador and in South East Asia and sometimes in West Africa. Artificially dried beans can be of poor quality due to contamination from the smoke of fires or because the cocoa is dried too quickly.
The simplest forms of artificial driers are convection driers or Samoan driers which consists of a simple flue in a plenum chamber and a permeable drying platform above. Air inlets must be provided in order to allow the convection current to flow without allowing smoke to taint the beans. These driers are simple to construct and have been used in Western Samoa, Cameroon, Brazil (the Secador drier) and the Solomon Islands.
Other artificial driers are platform driers using heat exchangers, where the hot air is kept separate from the products of combustion which pass to the atmosphere, or direct fired heaters, where the products of combustion mix with the hot air and are blown through the beans. These driers can use oil or solid fuels as a source of power. The addition of a fan forces the hot air through the beans and creates a forced draught dryer.
Another type of dryer uses conduction. Drying platforms built of slate or cement are heated at one end by a fire or heat source. Small versions of these using oil drums with flues embedded in cement were used in Cameroon at one time and were known as Cameroon Dryers. Heat distribution is not uniform with this type of dryer.
Other techniques have been used in association with the above to overcome the problem of turning or raking the beans in the dryer - stirring the beans in a circular bed or turning the beans in a rotary drum.
J.E.K. Amoah, Development of consumption, commercial production and marketing. Jemre Enterprises, 1995
R.J. Dand, The international cocoa trade. 2nd edition. Woodhead Publishing Ltd, 1999
G.A.R. Wood and R.A. Lass Cocoa. 4th edition. Longman, 1985
Cunha, J. Desempenho do secador 'burareiro'3*3 m na secagem do cacau. (Performance of the 'Burareiro' 3*3 m dryer for cocoa.) Agrotrópica 2 (3): 157-164, September-December 1990
Cunha, J. Desempenho do secador tubular com ventilacao forcada, na secagem do cacau. (Performance of the 'Tubular' dryer with forced air flow in cocoa drying.) Agrotrópica 3 (1): 39-43, January-April 1991