Development of a Cocoa Bean Roaster for Small-Scale Cocoa Processing

Cocoa is an important cash crop globally. It is a popular raw material in the pharmaceutical, cosmetics, and food industries. Despite many products and applications of cocoa, it is largely exported without any form of value addition. This is because the local producers lack machinery to add value to the produce. Imported roasters are very expensive and unaffordable by local cocoa farmers. Recently, Federal Government of Nigeria banned the importation of twenty-five products, including cocoa products. Consequently, there is urgent need to develop cocoa processing machines to leverage the government policy to enrich local farmers and investors in the beverage industry. This research is aimed at developing a cocoa roaster and evaluating same. Geometric modeling of a cocoa roaster was done with Pro/Engineer® Software. Theoretical design calculations resulted in the selection of 0.5 kW three phase gear motor and heating element of 1000 W forturning the roasting drum and heating same, respectively. Food grade stainless steel sheet and perforated sheet were used in developing the critical parts of the machine due to its high resistance to corrosion. Fabrication methods such as cutting, welding, drilling and grinding were used in developing the machine. Cocoa beans were sourced from Kurmi local government area, Taraba State, Nigeria, and used in evaluating the machine. 100 g of cocoa beans samples were roasted at 140, 145, 150, 155, 160 and 165 0C and corresponding roasting times of 45, 40, 35, 32, 32 and 28 minutes, respectively.  Input current to the temperature control panel and output current from the panel to the gear motor and heating element were measured with a clamp meter at different roasting temperatures. Specific energy consumption chart showed that energy consumption decreases at higher roasting temperatures and lower roasting times. As long as the aroma and flavour of the cocoa are preserved, it is more economical to roast at higher temperatures and shorter times. The developed 7 kg capacity cocoa bean roaster is suitable for small-scale cocoa processing.