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GTZ Root and Tuber Development Guides (1)

The Cassava Chipping Machine

Saving labour, improving quality
and increasing income

Eschborn, December 1998

Published by:

Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) GmbH

Project: "Integrated control of the larger grain borer - small farmers post-harvest systems"

Albert Bell, Section 4541
P.O. Box 5180
D-65726 Eschborn, Germany


The "Sedentary farming systems" Project, Sunyani, Ghana

Christian Henckes

P.O. Box 9698, K.I.A.

Accra, Ghana


with inputs from:

Otto Mück, post-harvest consultant
D-22885 Barsbüttel, Germany

Cover photo:

B. Schuler, DSE / ZEL
D-82336 Feldafing, Germany

Cassava chipping machine design:
GTZ / IITA Post Harvest Systems Newsletter No. 1

Gerlinde Quiter, GTZ, Section 4541
e-mail :




1. The Cassava Chipping Machine About this Leaflet

2. Manually Operated Chipping Machines

3. Benefits of Machine Chipping

4. Special Hints ...

5. Small Cassava Chips in the Kitchen

6. Where Can I Purchase the Chipping Machine?


GTZ's Root and Tuber Development Guides - their Objective

Post-harvesarvest operations are part of a system that includes all the steps, factors and actors from production to consumpttion. Therefore, a systems approach must be adopted when analysing constraints and introducing improvements. A methodology to analyse the constraints of post-harvest systems has been developed by the Food and Agriculture Organisation of the United Nations (FAO) and the Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) GmbH, with the support of the Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD) and the Group for Assistance on Systems relating to Grain After-harvest (GASGA). Applying the systems approach in the field of roots and tubers (R&T) has shown that there is considerable potential for promoting R&T processing and marketing in order to generate income.

GTZ's root and tuber development guides arewill be practice-oriented extension leaflets that show how rural families can make best use of R&T. Each issue of this series is is based on practical experience gained in the post-harvest research and development work conducted by many partners, especially in West Africa. Partners include the International Institute of Tropical Agriculture (IITA), national research institutes and universities and GTZ projects in countries such as Benin, Cameroon, Ghana, Kenya, Nigeria, Tanzania and Togo.

R&T commodities are of outstanding importance as staple foods and cash crops for the rural population in Africa. In some countries in tropical Africa, the nutrition of the entire population depends to a large extent on dishes prepared from R&T crops. Processing and marketing of R&T is one of the rare income-generating activities accessible to rural women, especially in Africa.

This series of guides is intendeds to help conserve and add value to R&T. Each leaflet highlights a particularly promising approach in R&T post-harvest technology, including operations such as storage, marketing or processing. The innovations presented in this series may help overcome traditional drawbacks, such as high perishability, the tedious nature of the work or the lack of profitability.

The following guides are in preparation: Cassava Flour Production, Processing of Yams and Market Oriented Yams Storage.

The economic viability of the proposals made in these leaflets has to be carefully assessed with regard to the specific circumstances. As the framework conditions differ widely, general recommendations on the profitability of an innovation cannot be made here. The extension workers involved in the promotion of root and tuber crops must be aware that the technical aspects of innovations are, in most cases, fairly simple to manage. Much attention must be paid, however, to their socio-economic implications (see Section 5).

The post-harvest activities conducted by GTZ and partner organisations in the area of R&T crops are part of the German Government's efforts to support the implementation of stipulations made in Agenda 21, such as:

Ö food security

Ö poverty alleviation

Ö advancement of women

Ö strengthening the role of farmers and

Ö promotion of sustainable agriculture

1. The Cassava Chipping Machine About this Leaflet


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.

Constraints in Traditional Cassava Chip Production

Traditional cassava chips are a common commodity in Africa's rural and urban markets. They vary from grey to brown in colour, and often have visible traces of mould and holes caused by insect attack. These characteristics often make them undesirable from a hygienic point of view. The production of traditional chips has a series of drawbacks that show up in subsequent steps of the post-harvest system:

ð Cutting

Cutting cassava manually produces rather large, irregularly shaped chips with poor drying properties (see below). Producing smaller chips with knives or machetes would require considerably more work. When large amounts of cassava roots are to be processed at a time, cutting can become quite a tedious task.

ð Drying

Manually cut cassava chips dry slowly and ununiformly because they are rather large and irregularly shaped. Depending on the climatic conditions during the drying period, the process may take 2 to 3several weeks. As a result, the chips often go mouldy, become soiled or are attacked by beetles. After drying, large cassava chips retain higher amounts of cyanide than small chips. Thus, the overall quality of traditional chips tends to be rather poor.

ð Storage and Transportation

Traditional cassava chips are bulky and not easy to package. This causes some constraints in storage and transportation: they require a lot of space, and larger quantities are difficult to handle.

ð Marketing

The ease with which traditional cassava chips may be marketed depends, among other factors, on their quality. Chips which are mouldy or have a lot of holes produced by beetles are difficult to sell and often have to be fed to farm animals because they are not accepted by humans. As a result, a considerable amount of chips may be lost for human consumption.

ð Detoxification

Depending on the variety, traditional cassava chips may contain high amounts of highly poisonous cyanide. Lengthy detoxification procedures, such as soaking in water for about 3 to 5 days, fermentation, boiling or roasting, are required during subsequent processing in order to avoid health hazards.


Chips produced by a chipper are generally of a higher quality than chips produced in the traditional way and will therefore be easier to market; they may even be exported. Traditional cassava chips are often regarded as a food for poor people in times of shortage. Chips produced by machine have a high potential for becoming a quality food and fodder, mainly due firstly to their quality, qualities such as the attractive white colour, less insect attack during storage and secondly, as they are less bulky, to the ease with which they may be stored and transported. This leaflet aims is to promote high-quality cassava chips as one of Africa's leading agricultural products in the future.

Women constitute an important target group. Initiatives in the area of R&T technology can reduce their workload and increase their income and social status. This leaflet will help facilitate the switch from a tedious manufacturing process to an efficient and profitable small-scale processing industry owned by women.

Target Groups

This leaflet primarily addresses agricultural extension workers who assist small-scale farmers. It may be used in participatory development programmes with families at the village level. The information contained here is designed to help develop solutions to specific problems in the post-harvest sector.

Women constitute an important target group. Initiatives in the area of R&T technology can reduce their workload and increase their income and social status. This leaflet will help facilitate the switch from a tedious manufacturing process to an efficient and profitable small-scale processing industry owned by women.

The task of extension workers is not limited to presenting and explaining innovations to the farmers. They should also act as an intermediaries between other stakeholders. They should, for example, be in touch with village craftsmen who are able to maintain and repair machines, such as the cassava chipper, and discuss with them the experiences of the users in order to introduce improvements.

They should also discuss their experiences with their superiors and raise the level of awareness of problems which must be solved by decision makers (see Section 5)..

The second main target group is policy and decision makers in the development process. The aim is to broaden their views on the economic potential of R&T commodities, which is often underrated.

2. Manually Operated Chipping Machines

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:

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.

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.

3. Benefits of Machine Chipping

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).

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.

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.

4. Special Hints ...

ð ... for related to the Extension Workers

Introducing innovations, such as the cassava chipper in food processing, will most probably be doomed to failure if the principle of participation is neglected in the extension approach. Past experience has shown that it is necessary to carry out a participatory analysis of the needs and develop the capacities of the target group in order to enable them to design appropriate solutions for specific problems. During a subsequent trial period, the farmers should be given the chance to confirm that the proposed solution is viable.

To ensure sustainability, support should not be limited to technical and financial assistance, but should focus on the management skills required to run the business profitably. The extension workers should closely follow up the performance of the business and organise competent support.

The question of ownership deserves special attention. As is the case for other methods of cassava processing, chips are usually produced by women. The introduction of machinery invariably arouses the interest of men and often leads to them taking over processing activities, although they have never previously shown any interest. The extension approach must target women specifically and, in addition to supplying a chipper, should, if necessary, include the provision of sufficient funds, the technical expertise to operate and maintain the machine, and the necessary management skills.

ð ... for related to the Advancement of Women

Self-help initiatives are the key to introducing successful innovations. Wherever individual efforts are not sufficient to overcome unsatisfactory living conditions, women can take matters into hands by forming groups. One of women could be entrusted with the management of their commercial affairs. Changes initiated by the target group are bound to be more sustainable, because of the strong feeling of ownership which arises as a result. Extension workers are expected to support these self-help initiatives.

More Special Hints ...

ð ... related to Policy Issues for Decision Makers

Semi-mechanical cassava chippers are unlikely to be financially successful if the economic framework conditions are not positively influenced by policy makers. It would be extremely helpful to create incentives by introducing and promoting standardised units for marketing the chips. In Ghana, for example, chips (kokonte in the local language) are sold in bags of different sizes. As the chips produced by machine are considerably less bulky than chips produced in the traditional way, a bag contains significantly more chip weight but is sold at the same price. This discourages many people from producing small chips. Standardised bags sold at a weight-unit base would be advantageous for the promotion of small chips.

Introducing and monitoring food-quality standards would also positively influence the production of chips by machine. Too many consumers have become accustomed to low-quality chips and do not necessarily find white-coloured chips without fungi any more appealing. Awareness of the risks associated with consuming low-quality food must be increased.

Extension workers can participate in this process by discussing their experiences with their suoperiors and by raising awareness at the target group level.

5. Small Cassava Chips in the Kitchen

The small, white cassava chips produced by machines are the ideal raw material for premium-class cassava flour that can be used for a range of both traditional and new dishes. Cassava flour may also be mixed with maize and other flours. The brilliant colour gives meals a very appetising appearance. Here areis just sonme examples of an inspiring recipes which hasve been developed by IITA.:

Cassava Cocktail Titbits


100 g (1 cup) cassava flour

100 g (or 200g cowpea paste) cowpea flour

2 egg whites

5 g (1 teaspoon) baking powder

3 g (½ teaspoon) salt

30 g grated onion (1 small onion)

700 ml (3 cups) vegetable oil


1 Wash the cowpea seeds, remove husks, dry and mill finely to make flour.

2 Add the onion and salt to the cowpea flour.

3 Beat egg whites until fluffy and add to the mixture.

4 Add the cassava flour and baking powder and mix well

5 Slowly add enough water to make a stiff dough.

6 Roll out thinly and cut into nice shapes.

7 Deep fry until golden.

Now put your feet up and enjoy them with a refreshing drink!

Fresh home-baked cassava bread offers a tasty alternative to bread from the bakery:

Cassava Bread


200 g cassava flour

300 g wheat flour

4 tablespoons of sugar

35 g margarine

12 g yeast

A pinch of salt

400 ml hand-warm water


1 Pour the water into a bowl, mix with the salt and yeast and set aside to rise.

2 Mix the cassava and wheat flour, add the margarine.

3 Add the yeast mixture and knead for 10 minutes.

4 Place the dough in a bowl, cover with a wet cloth and leave to rise until it has doubled in size.

5 Knead loaf again for 3 minutes.

6 Place in a buttered pan, cover with a wet cloth and let it rise again until it has doubled in size.

7 Bake the bread at gas mark 8 (200ºC) for 30 minutes.

Remove from oven and cool.

6. Where Can I Purchase the Chipping Machine?

To obtain your own chipping machine or more information, please contact the following addresses and/or all Sasakawa-Global 2000 offices in Africa:

Post-harvest Engineering Unit
Oyo Road
PMB 5320
Ibadan / Nigeria
B.P. 8202
Carre 473 / Godomey
Cotonou / Benin
Tel. 229-35 10 98
B.P. 40
Route de Lome
Ouidah / Benin
Tel. 229-34 13 35
B.P. 161
Route de Djougou
Parakou / Benin
Tel. 229-61 08 48
Sasakawa-Global 2000 - Africa
SG 2000

BP 04-1091 Cadjehoun

Cotonou / Benin

Tel. 229-30 04 59

Fax 229-30 06 37


SG 2000

PMB Airport

Accra / Ghana

Tel. 233-21-77 47 50

Fax 233-21-77 34 67


SG 2000

PMB 3130

Kano / Nigeria

Tel. 234-64-63 48 90

Fax 234-64-63 81 90


SG 2000


BP 7018

Ouagadougou / Burkina Faso

Tel. 226-31 18 26

Fax 226-31 26 58

SG 2000

Service Naional de la Promotion Rurale et la Vulgarisation

BP 576

Conakry / Guinea

Tel. 224-41 14 78

Fax 224-41 14 78

SG 2000

P.O. Box 495

Dar es Salaam / Tanzania

Tel. 255-51-36 882

Fax 255-51-36 882

SG 2000

c/o Ministry of Agriculture

P.O. Box 12771

Addis Ababa / Ethiopia

Tel. 251-1-51 05 84

Fax 251-1-51 08 91

SG 2000

Ministry of Development and Environment

BP 1093

Bamako / Mali

Tel. 223-22 83 62

Fax 229-22 39 14

SG 2000

BP 7525

Lome / Togo

Tel. 228-22 25 52

Fax 228-22 25 52

SG 2000

c/o Ministry of Agriculture

Agricultural Research and Extension Service

Asmara / Eritrea

Tel. 291-1-11 74 28

Fax 291-1-18 14 15

SG 2000

CP 4247

Maputo / Mozambique

Tel. 258-1-49 00 04

Fax 258-1-49 14 17

SG 2000

c/o Ministry of Agriculture, Animal, Industries, and Fisheries

FSSP Buildung

Entebbe / Uganda

Tel. 256-42-20 621

Fax 256-42-20 676

Y.W. Jeon C. Henckes

Post-harvest Engineering Unit c/o GTZ

IITA PO Box 9698

Oyo Road K.I.A.

PMB 5320 Accra

Ibadan (Nigeria) Ghana


B.P 8202 B.P. 40 B.P. 161

Carre 473 TEL: 34 13 35 TEL: 61 08 48

TEL: 35 10 98 Route de Lome Route de Djougou

Godomey Ouidah (Benin) Parakou (Benin)

Cotonou (Benin)

Published by

Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) GmbH

The "Integrated control of the larger grain borer in farmers’ post-harvest systems" project

Albert Bell, OE 4232

Postfach 5180

D-65726 Eschborn




The "Sedentary farming systems" project, Sunyani, Ghana

Christian Henckes

P.O. Box 9698, K.I.A.




with inputs from

Otto Mück, post-harvest consultant, Barsbüttel, Germany

Financed by:

The German Federal Ministry for Economic Cooperation and Development (BMZ)

The German Federal Ministry for Economic

Cooperation and Development (BMZ)