Design and construction of a coffee pulping machine.

Abstract

Coffee is primarily produced- by smallholders and is the main source of income for more than 500,000 Ugandan smallholders. In spite of high export earnings from coffee globally, coffee produced in most African countries fetch low prices compared to coffee from other continents due to poor quality coffee (Bibañgämba, 1989). This is as result of relying heavily on conventional processing which is cumbersome, expensive both to install and maintain and is prone to quality degradation if stringent processing standards are not followed. Additionally, lack or information on the performance of such equipments in respect to quality was cited as the main reason the production of poor quality coffee that fetches low prices in the international markets. As a result, most coffee farmers particularly individual local farmers who cannot afford to buy expensive imported coffee machines get low incomes from coffee sales which make very little difference in helping them out of poverty. This demanded an extensive research in the area of coffee processing in which the researcher came up with the design and construction of a manually operated coffee pulping machine that will effectively address the above mentioned problems that are currently faced by individual local coffee fanners and coffee processors. The prototype which is powered manually comprises of a hopper which contains fresh coffee cherries to be pulped and is welded on the outer drum. The frame of the prototype made of mild steel angle bar of thickness 2mm. The frame is of size 320mm x 200mmx 800mm. The pulping chamber comprises rotating pulping drum of length 300mm and a diameter of 25mm with spikes like projections on its outer surface, a shaft of 450mm long and diameter of 25mm passing through its centers and a fixed cylindrical drum of length 340mm and diameter 120mm. The pulping drum with a rotational speed of 60rpm it is attached to the handle which drives it in an anticlockwise direction to pulp coffee cherries. The machine was fabricated from locally sourced materials and it can be used in rural areas where there is no electric power supply. The output capacity of the fabricated prototype is 60k2/hr and its efficiency is 73% which is greater than that of already existing manually operated coffee pulping machine.