Design and construction of a semi-auto groundnut roasting machine.

Abstract

Groundnut roasting is one of the processing methods of groundnuts which increases its palatability by enhancing the release of aromas and flavors. The process inactivates trypsin inhibitors and eliminates allergenic proteins thereby removing the toxicity that is present in raw groundnuts. This study was carried out to design and construct a temperature controlled electric groundnut roaster to help groundnut processors to roast more easily and cheaply in a safe way. The groundnut roaster has been designed and developed from locally available materials for roasting of groundnuts and it has a capacity of 2.52kg/batch, the speed of the agitator is 55 rpm. The design of various machine parts was carried out by analyzing forces and effect of heat acting on them which helped in selection of proper materials to withstand the forces and heat to avoid failure. Better insulating methods are recommended to reduce on heat loss to the surrounding and to increase efficiency. Engineering drawings of the various components were drawn before the various components were constructed and then machine parts fabricated. A fully functional prototype resulted after all the above operations. Testing of the prototype was carried out and the figures revealed that the machine was 73.7% efficient. The groundnut roaster has a total cost of 1,150,000 UGX which includes all the taxes, cost of material, machinery and hired labor to construct the machine plus overhead costs. The cost evaluation analysis of the project was based on the payback period method, the project was evaluated to breakeven in 0.08 years and on net present value method with NPV of 1,759,196 UGX over a period of five years. The optimized roasting time and outer temperature of coil in the developed temperature controlled electric groundnut roaster is 15mins and 800C respectively. The developed groundnut roaster is suitable for roasting groundnuts with an efficiency of 73.7%