|Small Scale Processing of Oilfruits and Oilseeds (GTZ, 1989, 100 p.)|
|3. Case Studies|
Since 1982, a GTZ/GATE/DMA project has been engaged in Mali to develop and disseminate a system for processing shea nuts that improves on the traditional system. For this project an oven, a hydraulic hand press and a cake-expel stand have been developed by KIT. After introductory tests, the local production of the equipment has been set up and the equipment is being disseminated.
Organization and management at the village level
In villages, where shea nut trees grow, practically all the women collect and process shea nuts. The collected nuts become the personal property of the collector and are stored in her own pits. The processing is traditionally carried out at the level of the extended family by a group of women, who assist the collector. Occasionally small quantities are processed by individuals.
Adaptation of the shea nut press means that the processing has to be carried out at the village level. As the village women are generally organized and headed by a president, who is assisted by a group of elder women, this is quite feasible. However,first of all, the men, headed by the village chief, have to advise. The installation of a press is a village affair and has to be approved and backed by the men. The contribution by the village (50 % of the total investment costs for equipment and building) is raised by the men and the women.
The president and some representatives of the women supervise and organize the utilization of the press. They are also the owners of the press. A treasurer has to collect a small fee from the owner of the nuts in proportion to the quantity processed; money which is to be kept separate. It serves as a reserve fund to cover expenses for maintenance, repair and amortization. To have the fund administered in a formal way, a literate person should be available. Otherwise, a more informal administrative system should be implemented.
The press is installed under supervision of the GTZ/GATE project. The group appoints a few women (some older, some younger) to be trained in the operation and maintenance of the press. These women assist the processors and will train them in turn. The way in which the press is utilized is essentially a service system, by which the press is made available to the women of the village for a fee. The owner of the nuts is responsible for the processing and must provide the operating crew.
Process and equipment
The nuts to be processed are removed from the pit, pre-dried in the sun and decorticated. The kernels are subsequently pounded into a powder (with particles smaller than 5 mm). If the powder is dry, some water (about 10 %) should be added and left to be absorbed for an hour at least. The mass is divided into 5 kg batches and heated in a pot over a fire (to about 120°C) and kept hot for about I hour in the oven. The hot mass is poured into a preheated cage and pressed. When pouring, the mass should be divided in small portions of about I kg by means of a pressplate. After pressing, the cage is removed from the press and put on the expel stand to expel the cake, after which the oil extraction process is repeated, using the oil cake as raw- material. For this second pressing, the cake should be pounded and sieved (to be sure that all particles are smaller than 2 mm) and water (about 10 %) should be added. Finally, the extracted oil, containing some brown particles, is boiled with a little water and some juice of okra and lemon, to obtain a clear, white oil. The oil is left to cool down to form a solid fat, called shea butter. The cake is used as fuel.
The equipment required consists of:
- an oven, made up of a fire-place with a pot (no. 15, contents
401) and a heated box to hold a few buckets, covered with lids,
- a hydraulic hand press (based on a 30-ton lorry jack and equipped with two press cages with pressplates),
- a cake expel stand (to remove the oil cake from the cages) and
- some minor equipment like mortar and pestles.
The cost of the press with expel stand is F CFA 400 000, for the oven FCFA 40 000 and for the minor equipment around F CFA 10 000 (1987 prices). F CFA 50 are equivalent to French F 1.0, which is approximately US $ 0.15.
Results and experience
Total working time required for processing 10 kg shea kernels is about 10 man hours, of which about 3 hours are required for the pounding. A group of five women, which is a common case, would process some 50 kg of kernels per working day on average. Experienced groups can process up to 80 kg per day. Oil recovery is, depending on the quality of the nuts, between 35 % and 42 % on dry kernels, sometimes even higher.
Women are pleased to use the press, because:
1. heating of the nuts in a traditional oven for about three days at least can be omitted, which saves a lot of firewood and time;
2. the mass is easier to pound, while the crushing between stones can be omitted, which makes the work much faster and lighter and saves therefore time and energy;
3. very little water is required, which saves a lot of work;
4. the oil recovery, which of course depends on the quality of the nuts, is higher than traditionally (an estimate is about 13.5% on dry kernels; i.e. 38.5% average yield against 25 % in the traditional process);
5. the cake, which traditionally is discarded, can be used as fuel.
Another positive aspect is that this technology can be mastered by women and that the men are not really interested to take it over. The most probable reason for this is that the crucial steps, such as size reduction" and cooking", are still carried out in the traditional way, by pounding and a pot-over-a-fire respectively.
Shea nut processing is mainly carried out in the dry season, when the harvest is over. However, if money is needed and the rawmaterial is available, the women process oil in August as well. In a village in South Mali, 27 women are recorded as using the press and 1350 kg nuts were pressed in one year (an average of 50 kg per woman per year). In the same village, women collected other oil seeds as well as Niam Seeds (Lophira alata) for food-oil, Physic Nut (Jatropha Curcas) and seeds of the wild olive (Ximenia americana) for soap-oil. This can be seen as a first attempt towards a diversified production and will have an additional positive effect on the amortization of the equipment.
Although the women were trained with care, many women had difficulties with technical aspects; particularly with the hydraulic jack equipment. In some cases, the release valve was completely unscrewed and the hydraulic oil was lost. Besides, the women had to develop a sympathetic understanding for the equipment in order to prevent damage, for instance by pumping long strokes at a steady rate to conserve the pump and to stop at a certain maximum pressure to protect the press and save energy.
Also, an understanding of the process required time. Refresher courses are needed in order to keep the operation up to the required standard. Regular maintenance appeared to be required as well. Young villagers and some women were trained to carry out small maintenance and repair jobs such as topping-up with hydraulic oil or renewing a pump seal.
Technically, the press appeared to be not without its problems. The jack pump showed not only rapid wear at its seal, but also of its mechanical parts. On the other hand it appeared that the jack was not sufficiently well supported by the frame, thus causing the base of the jack to break. An improved pump for the jack has recently been designed. Also the frame will be reinforced. It is expected that these improvements will have positive effects.
Nevertheless, due to the advantages of the new processing system and the start-up of a service and maintenance programme, the demand for the shea nut presses is steadily increasing. By early 1987, the GTZ/GATE/KIT shea nut processing equipment had been installed in 35 villages in Mali. In addition, enquiries from neighbouring countries are increasing in number. Recently, the new technology has been introduced to Burkina Faso after technicians and extension workers had been trained in Mali.
It cannot be expected that the cost of investment of F CFA 440000 for the technical items (oven parts, hydraulic press and expel stand) can be paid in full by any village. Therefore, the equipment is normally partly subsidized by the project or other international organizations. The village usually is expected to build the accommodation (for approximately F CFA 100 000 ) for the press and to raise a certain contribution for the equipment. A small fee is asked from the women (e.g. F CFA 25 per 5 kg bucket) for a reserve fund to finance maintenance, repair and amortization.
For improving and facilitating the processing of shea nuts, an alternative solution is the use of a motorized grain mill. Because the processing of shea nuts makes the discs of the mill very sticky (requiring an extra cleaning procedure), many village millers are reluctant to make their grain mill available for the custom milling of shea nuts or alternatively demand much higher fees. If a motorized grain mill is available to the village, it is recommended to install a separate mill that can be driven by the same engine.
In Chapter 4, a financial appraisal is given based on the average price for nuts of F CFA 30 and for shea nut butter of F CFA 300 per kg, as prevailing in early 1987 in the rural areas of Mali. At that time, the local cost for milling of grain by a service mill was about F CFA 25 per kg.
Local production of equipment
To be able to start the distribution of the presses, local production had to be set up.
At first an existing construction company was given the opportunity to take up the production of the presses, guided by an expert from KIT. As it appeared that this company only wanted to continue if they could charge a 100 % profit, it was decided to establish a special production unit. A small partnership of craftsmen was advised by the GTZ/GATE project in establishing its own workshop with the press as the most important product. At present, this workshop manufactures the presses, supplies the spare parts and repairs the equipment, including the hydraulic jack. However, the supply of imported items, such as jacks and their spare parts, still gives problems. A reliable import line has yet to be organized.