Gate/GTZ 
Interdev Agroalimentaire  

The Cassava Chipping Machine

	Type de fiche	Techniques/Technologies
	Mise en œuvre	Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) GmbH  
 (Allemagne)
	
	Zone géographique	Afrique de l'Ouest; 
	Mots clés	EQUIPEMENT AGROALIMENTAIRE; MANIOC

	Public(s) cible(s)	agricultural extension workers who assist small-scale farmers & policy and decision makers

Problématique / Objectifs
The importance of cassava as a staple food in Africa has continued to grow because it possesses certain properties, such as tolerance to drought, and poor soils and even neglect. It is grown in over 30 African countries. Nearly 200 million people rely on cassava as a staple food, each person consuming an average of over 100 kg of the crop per annum. In certain marginal areas and regions fraught by civil wars and other crises, cassava is often the only food crop which is readily available. Fresh cassava roots, however, cannot be stored for longer than three to four days without being processed in some way.

Cassava chips are an essential raw material for countless dishes based on cassava flour. This leaflet describes how cassava chips can be produced more quickly, more efficiently and more profitably using manually operated cassava chipping machines. 

Description/Mise en oeuvre
Manually operated chipping machines have been developed by institutions dealing with applied technology, such as IITA in Ibadan, Nigeria or the Kwame Nkrumah University of Science and Technology (KNUST) in Kumasi, Ghana. Some improvements have been introduced by other development partners working with rural families at the grassroots level. The IITA model has been successfully promoted in several West African countries and has the following features: 
<p>
The chipper consists of the following parts:

- - - a wooden frame with a seat, a table from which the hopper is fed and a basin to collect the chips

- - - a circular metal chipping plate, which is attached to a wooden wheel on which a crank handle is mounted. The plate has a diameter of 35 cm and a number of holes, 3 mm in diameter with sharp, raised edges, that cut the chips from the peeled cassava root fed through the feed tray 

- - - a metal shaft resting on two bearings on which the wheel with the chipping plate rotates. 
<p>
Uniform chips of about 5 cm in length and 3 mm in diameter are produced by turning the handle in a clockwise direction and pressing the cassava root against the chipping plate. The chipper has capacity of about 60 kg of cassava roots per hour.

The machine is simple and portable, and can be maintained by people without an engineering background.

Extension workers may address village craftsmen in order to discuss and introduce the technical improvements of the cassava chipper.

The design of the shaft and bolt could be modified in order to prevent rapid wear and to achieve a fixed and durable clearance between wheel and frame. 

Experience with existing cassava chippers has shown that chipping plates made from ordinary iron corrode easily when they come in contact with the cassava roots. In order to avoid rusting, tempering of the chipping plates is recommended. The machine should be cleaned well after use. If the first chips that are produced show rust stains they may be fed to animals.

The frame of the chipper may be redesigned to make it adjustable in order to increase comfort and optimise the mechanical efficiency of the operator's physical work input. Increasing the weight of the wheel would raise the angular momentum and facilitate turning.

The problem of chip spillage, especially at the higher working speeds preferred by many operators, should also be examined in order to avoid losses and soiling. 

Résultats/Eléments chiffrés
Contact addresses can be found in the linked file!
Enseignements
Using manually operated chipping machines will bring about three major changes:

ð Improved Chip Quality
The chips obtained using the chipper are smaller and therefore dry quicker and better than traditional chips. They also contain less cyanide. As a result, the chips have a low moisture content that makes them easy to store, and they have an appetising whitish colour. During the short drying process, they stay cleaner and are less prone to mould and insect attack than traditional chips. Small chips are easier to store. Trials conducted in Ghana have shown that insect attack was reduced. Generally, chips are subsequently processed into flour, from which a wide range of dishes may be prepared. As the quality of the chips is higher, the flour derived from small chips is also much superior in quality.

Best results are obtained using varieties low in cyanide. Other varieties should be detoxified by fermentation before chipping (by soaking in water for about 3 to 5 days). 
<p>
ð Reduced Workload
The drying time is considerably reduced. Experience in Northern Ghana, for example, has shown that chips produced by machine take only 3 to 4 days to dry (when placed in layers 2 to 3 cm deep),, compared to 2 to 3 weeks for chips produced in the traditional way. As a result, less handling is required in the drying stage. 

Drying is most efficient on cemented surfaces or on dark foils. The chips must be stirred in order to achieve best results. When placed in layers 2 to 3 cm deep (as recommended), the chips need only be stirred up to three times a day. If possible, Ddrying should not be carried out on the roadside or in other dirty places. Animals must be kept away from the drying area. 

To produce flour, traditional cassava chips must be pounded before being taken to the mill. Small chips obtained from the chipper can be milled directly to produce a very fine flour for immediate use. As, aso that second, or even a third, milling process is not necessary, the wwomen or children who generally have to do this job save a lot of time and energy. 

Furthermore, small chipsthe cassava is are easier to store and handle, as one bag of small chips is equivalent to three bags of traditional chips. 
<p>
ð Higher Incomes
IncomeOutputs can be increased and work made easier using a manually operated chipping machine, and the quality of the chips is higher then in traditional production. Operating a chipping machine as a small-scale enterprise that provides services to the farming community of the neighbourhood or village could provide a good source of income. Cassava chipping is generally a task carried out by women or children; the improvement in quality brought about by the use of machines will help to increase their income while decreasing their workload. (see section 5).

The production of high-quality flour from small chips may help to create more demand for all kinds of food based on cassava flour. This may raise the incomes of all those involved in processing and trading cassava.

Auteur : Carolin Bothe
Saisie le : 17/01/2002
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	Contact	Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) GmbH  
 , GTZ
Postfach 5180, 62726, Eschborn
Tel.:++49 (0)6196 79-0, Fax: (0)6196 79-1115, E-mail: firstname.lastname@gtz.de
Site web: http://www.gtz.de/

	Références Bibliographiques	GTZ (Albert Bell, Christian Henckes) .- GTZ Root and Tiber Development Guide -
The Cassava Chipping Machine