Comparative Study of Solar Drying of Cocoa Beans: Two Methods Used in Colombian Rural Areas

Abstract

In Colombia, the production of cocoa beans is an important export business classified as “fine cocoa” type by the International Cocoa Organization (ICCO). Drying for agricultural products is one of the most cost-effective applications of solar energy and the drying methods for cocoa beans are traditional and vary with geographical locality. Cocoa beans are dried after fermentation in order to reduce the moisture content, being the open-air solar drying (direct solar dryer) and the greenhouse drying (plastic roof solar dryer) two methods used in colombian rural areas. However, in the Caribbean region of Colombia is widely used, by rural farmers, the open-air solar drying. This method is economic but susceptible to contamination with foreign materials, insects and rodents, affecting the quality of the beans. This work presents the construction of a plastic roof solar dryer for drying cocoa beans in a farm that use direct solar dryer. The moisture content of the cocoa beans were determined using a MB 45 Halogen Ohaus moisture analyzer. The moisture content was reduced from 58 % to 7 % in 6 d for the open-air solar drying (drying constant, k = 0.76 d-1), while the greenhouse drying took only 4 d (drying constant, k = 1.68 d-1) and produced better quality cocoa beans, protected from direct solar radiation, environmental pollution and animal contact. Technical and economical results indicate that greenhouse drying is feasible for rural farmers in the Caribbean region of Colombia.