Malian peanut sheller

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The Malian peanut sheller in Uganda, 2005

The Malian Peanut/Groundnut Sheller is a simple hand-operated machine capable of shelling 50 kg of raw, sun-dried nuts per hour. It is low cost (requiring less than US$50 in materials) and made of concrete poured into two simple fibreglass molds, some primitive metal parts, one wrench and any piece of rock or wood that might serve as a hammer. It accepts a wide range of nut sizes without adjustment. If necessary, adjustment is quickly and easily done. In Mali, it is estimated that one machine will serve the needs of a village of 2,000 people. The life expectancy of the machine is around 25 years. Its design is public domain and it is expected that local experience will improve the design as time goes by. A non-profit organization known as the Full Belly Project offers technical assistance to non-profit or commercial groups planning to use the design in their programs.

1 How it works
2 History
3 Applications
4 Awards
5 See also
6 References
7 External links

[edit] How it works

Diagram of the shelling machine

Traditional shelling machines press the nuts through slots to release the kernels from the shell. This works well with nuts roasted in the shell, but poorly if they are sun-dried. The machines are generally made of wood, to close tolerances, by skilled craftsmen. They are expensive, generally require several people to operate and have limited capacity and lifespan. The Malian Sheller, however, rolls the nuts in an ever narrowing space between two concrete surfaces, at ever increasing speed. The machine is loaded with about a litre of nuts. The handle is then turned quickly for about 20 seconds. The kernels and shell fragments fall into a shallow basket and are later separated from the peanuts by a process called winnowing.

[edit] History

In the summer of 2000, an engineer from North Carolina named Jock Brandis visited a Peace Corps volunteer promoting the increase of protein in children's diets in southern Mali. Both were unhappy to see the widespread introduction of cotton as a cash crop and the rapid loss of soil fertility that was already evident. At that time, there were conversations with the local Women's Co-operative, looking for a more profitable crop to take to market.

The solution to all three concerns was the increase in peanut cultivation. The problem was that to save fuel, peanuts were traditionally sun-dried, shelled and then roasted. A roasted shell is quite fragile but a sun-dried shell is very tough and difficult to break open by hand. The engineer agreed that, after returning to the US, he would buy and ship an appropriate shelling machine to the village. Brandis' search failed to produce a suitable machine, but with the help of Tim Williams at the University of Georgia (Griffin) and individuals in Wilmington, North Carolina, the Malian Sheller was invented. Field tests near Sikasso, Mali, in 2001 revealed some design and fabrication flaws, which have since been eliminated. During the trip, a film called Peanuts was made.

[edit] Applications

Studies in the field have shown that one machine is capable of processing enough peanuts to feed 1,000 people. With a few manual adjustments the machine is also capable of shelling winged beans, neem nuts (from neem trees, Azadirachta indica, also known as margosa) and a variety of other nuts found throughout the world. Research is also going into creating another hand-powered machine for making fresh soy milk from soybeans.