Development and evaluation of a continuous cocoa pod breaker

Abstract

Cocoa (Theobroma cacao) is a commercial plantation crop in India. It is the main raw material in the production of chocolates, cosmetics, health drinks, pharmaceuticals etc. The cocoa beans which are embedded in a mucilaginous pulp inside the pod consist of two parts- seed coat and seed cotyledon. Seed cotyledon is the material in which characteristic flavour and aroma produced during fermentation. At present, cocoa pod breaking and bean extraction from crust pod are done manually by using sickle which is a labour intensive method. Manual chopping could increase the number of damage bean which leads to fungal attack. In order to eliminate the drudgery involved in manual cocoa pod breaking, avoid injury to workers, increase efficiency and to ensure high quality products, an attempt was made to develop a continuous cocoa pod breaker. Before the fabrication of machine, the engineering properties of cocoa viz., physical, mechanical and frictional properties of fresh cocoa pod were determined. Physical properties studied were size, shape, mass and density. The mechanical and frictional properties viz., compression test, angle of repose and co-efficient of friction were determined as per the standard procedures. The continuous cocoa pod breaker consists of hopper, metal rollers, chute, rotating cylindrical strainers, frame, prime mover and pulleys. Cocoa fruit was fed manually in to breaker unit through hopper. Gap between the rollers was set so as the cocoa kernels were not damage during the pod breaking process. Tangential force of the roller pushed the cocoa pod towards the gap resulted in breakage. Cocoa pod, kernels and placenta then discharged to strainer through chute. Rotation of strainer separated the cocoa kernels from cocoa pod and placenta, and passed through the pores of the strainer. It was then collected and could be directly send for fermentation process. The broken pods were remained above the strainer and got separated.Performance of the machine was evaluated in terms of capacity, energy requirement, percent bean damage, per cent bean recovery, shelling efficiency and machine efficiency. The average capacity and breaking efficiency of cocoa pod breaker was 550.5 kg/h and 95-98 percent, respectively. Bean damage percentage was 0.5 per cent. The shelling efficiency and beans separation efficiency of the strainer at inclination, 45° 96.42 and 86.5 per cent, respectively. The performance of the developed cocoa pod breaker was compared with traditional method of pod breaking, the total time required to break 100 kg cocoa pods and collect the beans for mechanical and manual method was 10.44 and 50.17 minute, respectively. The field evaluation of the developed machine was done with two cocoa varieties viz., Criollo and Forastero. The performance of the machine was evaluated based on its capacity, per cent bean damage, efficiency of cocoa pod breaker and energy requirement. From the field trail it is understood that, the efficiency of the machine is higher for Criollo variety as compared to Forastero variety. The fermentation studies were conducted in artificial fermentation chamber, poly house and ambient condition and it was compared with three different environmental conditions (ambient, poly house and fermentation chamber). The effects of treatments on dependent variables like temperature, pH, moisture content and microorganisms during fermentation process were studied. In this study, fermentation of cocoa beans on all methods in the artificial fermentation chamber found the best among the other treatments for the production of good quality cocoa. Similarly, the box method was found the best among the other treatments for the production of good quality cocoa. The cost of operation of cocoa pod breaker of 550 kg/h capacity was estimated as Rs.74.42 /-