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close this book Food Chain - Number 22 - January 1998
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View the document Greetings
View the document Research notes - utilisation of tomato processing by-products
View the document Shea nut processing - possibilities and problems in the choice of technology for women
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View the document Weaning foods
View the document Latin America pages
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Shea nut processing - possibilities and problems in the choice of technology for women

Shea butter also has an export market for use in cosmetics, pharmaceuticals and confectionery.

The role of women in technology is a topic of great interest to many working in rural development. Many periodicals have published special editions on the subject with specific emphasis on improved working conditions for women. The UNIFEM Food Cycle Technology Manuals describe technology alternatives for small-scale processing of various commodities and illustrate their application through case studies However, it is often difficult to find a suitable solution for a particular group of women. This article by Domien Bruinsma not only illustrates the complexity of the problems involved, but also points to the opportunities that exist in the selection of technology, based on a case study of shea nut processing.

Very often, insufficient basic information is available to allow the evaluation of all possible technological alternatives, so making it difficult to meet the specific needs and demands of women involved in a particular activity. Sometimes, a technology which appears to be appropriate, will be too expensive and of too great a capacity to be profitable and manageable by a group of women. On analysis, two distinct problem areas can be identified. The first relates to the processing capacity of the equipment which, to run profitably, requires the processing of a minimum amount of raw material. Not only does raw material of the correct quality have to be available in sufficient quantities, but also a market has to exist for the final product. Secondly, technical requirements and maintenance activities frequently demand business management skills which often exceed the women's capabilities. The introduction of technology therefore needs to be closely monitored and supported.

Clearly then, the selection of an appropriate technological solution is a complex problem. To arrive at an appropriate choice, it is essential to include those requesting the technology in both a socioeconomic and technical evaluation of the alternatives available.

THE IMPORTANCE OF SHEA

The shea tree (Butyrospermum parkii) grows abundantly in semi-arid areas of west Africa. Countries with the highest density of shea trees are Mali, Burkina Faso, Togo, Benin, Nigeria and the Sudan. Each tree can produce on average 15 to 20kg of fresh fruit, which yield 3 to 4kg of dry kernels. The kernel contains 42-48% oil of a relatively high melting point. Extraction of this oil provides an edible shea butter which is used in cooking.

Shea butter is the main source of fat in the rural zones where it is produced. It is used in food, soap manufacture, traditional drugs and cosmetic products. It has also long been used for lighting and although the use of kerosene lamps is increasing, shea oil lamps are still commonly used. Shea butter also has an export market for use in cosmetics, pharmaceuticals and confectionery.

While almost all rural women in shea areas harvest and store the fruit at the beginning of the rainy season, the methods they use for storing and preparing the nuts vary from region to region. Harvesting, preparation and storage are carried out by individuals, but processing is more often a group activity and, according to local customs, it is organised at family or group level. During the dry season, the women typically spend two days a week on butter production either for family use or for sale in the market.

The pre-treatment drying and pounding differ from one region to another and this can have a considerable influence on the final butter quality.

BUTTER PRODUCTION

The production of shea butter is part of village tradition. During processing the women sing and clap their hands for encouragement. This is necessary because the work is arduous. Typically the process involves the following steps. First the nuts are dried and shelled and the kernels removed. The kernels are then crushed and the crushed material, called grits, is roasted in a pot over a fire. The women then pound the roasted grits in a mortar producing a coarse paste. This is then finely ground between two stones to produce a smooth, reddish brown paste, which is put into a large container. Water is added and the mass is churned manually until the butter floats and becomes a whitish colour. The butter is separated and is washed repeatedly with warm water. It is then placed in a pot and heated to evaporate any remaining water. During this last step any fibrous impurities settle at the bottom of the pot. The liquid butter is collected in a container where, upon cooling, it solidifies. The pre-treatment drying and pounding differ from one region to another and this can have a considerable influence on the final butter quality. The actual extraction procedures also vary and nowadays mechanical milling, churning and pressing are becoming more common.

There are several stages where mechanisation and improvement of the process would he possible. This article describes different improved technologies which have been tested by development projects. All are intended to reduce the most arduous and dirtiest tasks; manual pounding, grinding and churning. In some cases the use of mechanical presses to extract oil has been chosen. In others pounding has been replaced by power milling followed by traditional manual churning. Other systems also mechanise the churning process. The five alternatives evaluated in this article are summarised below:

1) Many villages now have a private or community mill which can replace traditional pounding and grinding.

2) In Ghana, a small engineering company, 'SIS Engineering,' has developed a mechanical churning and washing machine with co-operation from the GRATIS project (Ghana Regional Appropriate Technology Industrial Service).

3) In Mali another extraction system, the Mockarite, involves the use of a centrifuge to replace churning and washing.

4) Two types of press, a spindle press and a hydraulic press, have been tested and distributed in Burkina Faso and Mali to replace all processing steps from pounding to washing.

5) A manually turned roaster has been developed to replace the traditional pot over a fire method.

Table 1 summarises each of these alternatives compared with the traditional system and shows indicative time savings. About one hundred hydraulic presses have been installed, mainly in Mali, and over twenty spindle presses in Burkina Faso. Three Mockarite machines are operating in Mali and about twenty SIS Engineering machines in north Ghana.

Table 1

Method

A

B

C

D

E

F

 

Traditional

Mill

SIS Eng

Mockarite

Spindle Press

Hydraulic Press

Total time (mine) to process 10kg shea kernels

516

219

117

87

232

192

Time saved over method A

-

58%

77%

83%

55%

63%

Capacity - kg per day

-

400

260

420

125

125

Capital cost CFA

-

1,100

988

5,030

596

996

Break-even tonnes/annum

-

30-40

50

50

17

25

Days operation for break even

-

75-100

200

120

140

200

COMPARISON OF THE DIFFERENT METHODS

An important claim of the mechanised alternatives is that they reduce processing time. Various information sources have been used to calculate the duration of the different operations shown in Table 1. For the traditional method, the mill and the spindle press information is used from the Karite Shea project in Koudougou, Burkina Faso. Sources of information about the Mockarite are CMDT (Compagnie Malienne de Development des Textiles) and CEPAZE (Centre d'Echanges et Promotion des Artisans en Zones a Equiper, Paris). GRATIS information is used for SIS Engineering equipment. In order to compare the different processes we need to examine each in a little more detail and the assumptions that have been made.

In methods B. E and F. crushing is carried out using a manual crusher developed by the shea project. This machine resembles that used to shell groundnuts. In the SIS system, (method C) - a motor driven mill is used to grind the kernels. All the systems are based on the use of a manual rotary roaster, except for the SIS machine which uses the traditional cooking pot. When using the spindle press (E), rotary roasters are replaced by solar ovens which provide sufficient pre-treatment. It has been found that the hydraulic press requires slightly less labour than the spindle press.

The traditional system of boiling, purifying and decanting to clarify the butter, is used throughout without any improvements. For the purpose of the calculations, it is assumed that the product obtained before purification is similar in all cases. In fact, there are slight differences in quality at this stage. For example, the Mockarite provides a clearer product.

It has been noted that women in certain villages, who know that their nuts are of a poor quality, are prepared to wait a long time to use the press.

BENEFITS OF IMPROVED TECHNOLOGIES

All these improved technologies yield higher quantities of butter than the traditional method (35-42% compared to 25 - 28%). However, if compared to large-scale processing the yields are low. One positive aspect of the presses is that it is possible to obtain butter from nuts which could not be used in the traditional method. It has been noted that women in certain villages, who know that their nuts are of a poor quality, are prepared to wait a long time to use the press. Interestingly other women with nuts of a good quality tend to use the traditional method rather than waste time waiting.

An attempt was made to compare the technologies in economic terms by including investment costs, processing capacity and the reduction of the time women have to spend on processing. In this respect, a SIS Engineering machine or a mill is the most efficient. The Mockarite, despite giving the greatest reduction in workload, is the most expensive option. However, this kind of economic evaluation is over-simplistic and should not be used as the sole measure of a system.

There are differences in quality depending on the method used, but to make comparison simpler, this aspect has not been evaluated. The concept of 'task difficulty' also needs to be considered. For example, presses reduce the amount of work but still involve heavy manual operations. The type of physical movements required to operate the two types of presses are very different and so are rated differently. In general, women find it more difficult to operate a hydraulic press than a spindle press.

To date, operating costs have not been included in the calculations, but clearly for all motorised procedures the cost of diesel has to be taken into account. The Mockarite and the SIS Engineering machine have the greatest fuel consumption. On the other hand, the reduction in wood and water consumption has to be offset against diesel costs. The greatest savings in wood use are noted when using the Mockarite and to a lesser extent, presses. Ease of operation and maintenance are other factors requiring consideration. In Mali, for example, the majority of the hydraulic presses are no longer in use due to problems maintaining the hydraulic jack. Spindle presses appear to be both easier to use and maintain.

Finally, a very important consideration is the minimum throughput required to run the equipment profitably, in addition to the complexity of the technology, together with its management and maintenance requirements. There is insufficient data available to calculate a precise break-even point for each process. All five systems have different costs and different daily throughput. Whilst the spindle press is the cheapest system, it has the lowest throughput. Whereas although the motorised mill is expensive, it has a much higher throughput rate and can he used to mill other crops. The break-even point is probably lowest for the spindle press (around 17 tons of nuts/year, corresponding to 140 days operation/year). The hydraulic press has a break-even capacity of 25 tons/year, i.e. 200 days of production. For this reason it is only economic if other oilseeds are processed. The break-even point for mills is generally between 30 to 40 tons/year and they need to be in operation for 75 to 100 days. The advantage of mills however, is that they can be used to mill cereals when shea is not available. The Mockarite has a break-even point of about 50 tons/year and must be operational for 120 days, with the possibility of being used as a cereal mill as well. For the SIS Engineering machine, the figures are probably about the same, hut this means that it needs to be in operation for 200 days and probably also needs to be used to process other oilseeds and/or to mill cereals.

The advantage of mills however, is that they can be used to mill cereals when shea is not available. Any companison of the methods will only be valid if it is carried out with the target group and takes into account their particular circumstances.

EVALUATION WITH THE WOMEN

Any comparison of the methods will only be valid if it is carried out with the target group and takes into account their particular circumstances. The women should compare for themselves the advantages and disadvantages of the various alternatives, as well as the organisational aspects of the business activity. It is extremely important that information is exchanged with other villages and that their equipment is tried out during visits between villages. It was demonstrated how important women were during the development stage of the SIS Engineering machine for churning. Their observations with regard to yield and butter quality are extremely important. The women know best how to judge the quality and yield of the end product by the traditional method and this knowledge is handed down from mother to daughter from one generation to the next. They also understand the market requirements and opportunities. For this reason, it is important to communicate with the women producing the butter to discuss any new technology. Finally, women can give an estimate of the economic value of the investment in terms of time saved and the reduction of arduous work. In this way women can indicate what price they would be willing to pay for the labour reduction achieved.

In conclusion, it is not a simple matter to evaluate the advantages and disadvantages of a particular type of technology. The best option may vary from one situation to another. For example, a large wealthy village which already owns a mill, may well decide to purchase a second mill exclusively for processing shea, but driven from the existing motor. A village with no mill, but with sufficient purchasing power, may opt for either a Mockarite or a SIS Engineering machine. The quantity of shea, available and the amount of organisational experience at village level will also influence choices. A village which does not have the purchasing power to run a mill profitably, or for motorisation in general, but with sufficient shea, could consider the acquisition of a spindle press. The most important point is to involve the women processors and allow them to genuinely gain experience with the technology and to have sufficient time to come to a decision. Finally, it is essential to choose a system of ownership and management which will allow the project to survive.

This article was kindly sent in by Domien Bruinsma, Gruttoweide 119, 6708 BE Wageningen, The Netherlands. Any readers requiring further information should contact the author.