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DEVELOPMENT IN POST-HARVEST PROCESSING TO
SUPPLY URBAN MARKETS:
A SURVEY OF THE YAM CHIPS SECTOR IN WEST AFRICA
1 |
CIRAD-IITA Yam Research Co-ordination Unit, Cotonou, Benin |
2 |
CIRAD-SAR, Montpellier, France |
3 |
National University of Benin, Faculty of Agronomic Sciences, Cotonou, Benin |
4 |
National Institute for Food Crops (INCV), Lomé, Togo |
5 |
National Root Crop Research Institute (NRCRI), Umuahia, Nigeria. |
Background
Yam is a valued food in West Africa, but its consumption in its fresh tuber form is very limited in urban centres. This is because it is a seasonal and perishable crop that can not be made available in the urban markets all year round, a fact that makes it more expensive than other starch-based foods. With urbanisation, an original yam chip chain was observed to have developed in some countries. This is a stabilised product obtained from small pre-cooked and sun-dried tubers. The chips are mainly eaten in paste form ("amala" or "telibo") prepared from the flour obtained by grinding them. In order to better appreciate its importance and understand how this still little known sector functions, a survey of the consumption of yam-based products was carried out in the urban centres of three countries (Benin, Western Nigeria, Togo). The situation differed in each country. While in Togo and Benin the staple food is still maize, "amala" seems to have penetrated the eating habits of the Beninese people as an alternative that is eaten more often than fresh yam. In the part of Nigeria where the survey was carried out, the consumption of amala predominated. According to the people, they eat yam chips derivatives because of its taste, availability, and ease of preparation. The development of this sector in other yam producing countries through the transfer of the appropriate technology, will help reduce the constraints encountered in the marketing of fresh tubers.
Yam in West Africa
The rapid pace of urbanisation in West Africa (almost 7% per annum) may act as a catalyst to food crop production in the African continent in one basic way: the development of sustainable intermediation systems (marketing, transportation, processing) between urban and rural areas. These systems should be able to guarantee outlets for farmers, thereby encouraging them to increase production, and at the same time make available, on a permanent basis, products that are adapted to the eating habits and budget of urban consumers.
In the Sudan savannah and the humid tropical zone, yam has a great challenge potential as a food and plant crop. It has been shown that it is one of the richest tropical plants in terms of calorific (de Vries et al, 1967) and protein (Idusogie, 1971) value.
In 1995, African yam production was estimated at almost 33 million tons per year, more than 31 million of which was produced in West Africa alone, the larger share being produced by Nigeria (23 MT). Ivory Coast (2.8 MT), Ghana (2.2 MT) Benin (1.3 MT) and Togo (375,000 T) are also major producers (FAO, 1996). Still according to FAO statistics, between 1989/1991 and 1995, production in the continent increased steadily by 50%, which at best contradicts the folk tale picture that Coursey already rejected (Coursey, 1981) of a crop with uncertain future, handicapped by high production costs and difficult to preserve.
In this region, yam is an ancestral crop to which the farming community is particularly attached. This plant and food crop therefore plays an important social and cultural role which makes it the African Yam Centre (Miège, 1957). Yam is also the source of food security in the region because its plant is less sensitive to climatic changes than the cereals cultivated in the same zone. Although originally from the Gulf of Guinea (Nigeria, Benin) (Coursey, 1976), yam cultivation is also developing in the humid tropical zones of Central Africa. Yam is now present within the agricultural systems of the Central African Republic (250,000 t), Chad (240,000 t) Gabon 120,000 t) and Zaire (315,000 t) (1995 data), either as a main crop, or as a diversification crop.
Yam consumption is high in the production zones where it is recognised to have a high calorific value. Its consumption is also relatively high in urban areas in spite of competition from other products (cassava, maize, sorghum, rice, wheat). Therefore in Africa, yam continues to be highly valued by city dwellers and has a certain prestige. It helps to expand the dietary pattern which is the trend in the consumption habits of urban centres (Bricas, 1993), especially for the part of the population that is not originally from the traditional production zones. In West Africa, yam chip marketing is extending beyond producing countries towards towns in the Sahel region (Bamako, Ouagadougou, Niamey) where it can be seen arriving from coastal countries, and where its consumption is usually introduced in popular restaurants.
Yam chips
Despite the fact that yam was mostly eaten in its fresh form, the processing of yam tubers into chips for domestic use has been a long time practice in all yam producing zones. Farmers stored part of their production in their kitchens after treatment to cover the periods of scarcity. This technique involves peeling the tubers, pre-boiling them in water containing natural substances which later act as fungicides and insecticides. Then they are dried in the sun preferably during harmattan. It is not in all cases that the tubers are pre-boiled, especially in Nigeria (Ezeh, 1992).
The preparation of "Amala" is described in Figure 1
| Fig.1. |
Processing of yam tubers into chips,
flour and "amala" (After the Nutrition and Agro-Alimentary Sciences Department,
FSA-UNB). |
 |
In this case, the possibility of preservation is limited to a few weeks while they can last for more than one year when the tubers are boiled before being dried. They are mainly sold in the form of small tubers dried whole or in chips to urban markets. More complicated dishes like "wassa-wassa" (flour granules) are also well known in the sub-region, as well as "tubani" which is mixed with beans flour, in Ghana.
Yam chips processing is a very common tradition in Ife, Ilesha and Ede, all in the western part of Nigeria (Adisa, 1985; Ige, 1981). However, the Nigerian and Beninese yam supply sector still focused mainly on fresh tubers until some twenty years ago. Yam-based products were still considered as domestic products in Nigeria until a few years ago (Coursey, 1979). Yam chips did not appear in the agricultural statistics of Benin until towards the end of 1970 (Dumont & Vernier, 1997).
The limitations of the fresh yam sector
Yam is still almost exclusively marketed in the form of fresh tubers in other countries. This situation presents a lot of disadvantages including the following:
* |
Because of the quality of fresh yam demanded by consumers, farmers give priority to the production of the large tuber variety which is good for pounded yam. The cultivation of this variety requires highly fertile soil and the slashing-burning of a large land area. It also involves a lot of work, especially for ridging up the plants to enable the tubers to grow in size in a light soil. However, because of the pressure on land, the arable area tends to reduce, and plant rotation to increase. Given this situation, it will be difficult in the long run to continue to increase the production of this type of yam in such a way as to meet increasing demand. |
* |
In contrast with cassava which can be harvested all the year round, yam is a seasonal crop and is difficult to preserve beyond a few weeks after harvest. In the absence of stabilisation techniques, post-harvest losses (rotting, sprouting) can be high especially where the most popular varieties are concerned. These losses can reach almost 50% of production in six months (Coursey, 1967). |
* |
Due to the above reasons, the availability of fresh yam on the market is seasonal and consumer prices vary considerably during the year. As shown by ONASA (National Organisation for Food Security) data in Benin (Fig. 2), the price variation factor may range from 1 to 6 during the year. |
* |
Because of the high moisture content of fresh tubers (60 - 75%), marketing is handicapped by high transportation costs. |
* |
As a result of all these constraints, the urban consumer pays a relatively high price for fresh yam when compared to other starchy foods. The average annual prices of starchy foods in the Cotonou main market (Dantokpa) and the Parakou market, the major production areas, are presented in table 1. |
| Fig.2. |
Yam price trends according to
product on the Parakou market, Benin (ONASA data; eq. dm = equivalent in dry mass). |
 |
The advantages of the yam chips sector
When compared with the fresh yam sector, yam chips offer a lot of advantages:
* |
The quality of chips demanded by consumers is different from the one required for pounded yam. Small tubers weighing between 300 and 400 kg are preferred because they dry more easily, and are consequently considered by consumers to be of better quality. As a result of this, producers give priority to the production of the varieties popularly known as "Kokoro" in the three countries (D. Cayenensis rotundata) and that have several small tubers (better known as "Alassora" in Togo). These also appear to require less soil fertility than the "pounded yam" variety, are generally early maturing, and are better adapted to stabilised cropping systems. They also require smaller mounds, thereby reducing workload. As a result, the "kokoro" varieties seem to be better adapted to new developments than the conventional varieties, as evident in the demographic evolution and the gradual change to settled farming systems as a result of demographic growth. |
* |
Processing into yam chips makes it possible to stabilise the product, thereby reducing considerably post-harvest losses. Yam chips can be preserved for over a year, and are therefore regularly available on the urban market. Going by ONASA data, price variation in Benin does not exceed a factor of 1-2 during the year (see Figure 2). Difficulties are however still being encountered with the sun-drying of a large quantity of tubers because they only dry properly during the harmattan season (low relative humidity). |
* |
These difficulties result in the production and sale of tubers that are sometimes poorly dried and blackened by moisture. During storage, the chips are often infested by boring insects (Adisa, 1985) which cause considerable damage in a few months. The most common among these are Sitophilus zeamais Motshulsky (Col: Curculionidae), Dinoderus oblonguntatus Lesne, and D. minutus Fabricius (Col: Bostrichidae) as well as Palorus subdepressus Wollaston (Col: Bostrichidae) (G. Goergen quoted by Dumont, Vernier, 1997). |
* |
Yam chips have a moisture content of about 10 to 13% (as against 60 to 75% in fresh tubers). The transportation cost per dry unit is therefore much less. |
* |
All these characteristics make it possible for consumers to obtain the chips at a comparatively cheaper cost than fresh yam. |
* |
Since the devaluation of the CFA franc, yam chips in Benin have settled at a price ranging between that of cassava or maize and of rice, wheat or fresh yam (see Tab. 1 and 2). |
* |
Finally, the advantage of yam chips is that they offer opportunities for new culinary use, for example the possibility of processing the flour into granules or incorporating it in starchy products like biscuits, baby food, beverages, etc. Some of these processing methods are already being explored by small scale enterprises, especially in Benin (production of sifted yam chip flour) and in Burkina Faso (production of "yam couscous"). |
In several ways therefore, the yam chips sector would appear to be very interesting as regards its ability to offer alternatives to the foods eaten in urban centres, by upgrading local production, and with due regard to new developments in the farming system. This study on the sector was embarked upon especially in order to obtain more information on how it can be developed in other yam producing countries where yam supply to towns is still mainly in the form of fresh tubers.
Tab. 1: |
Mean
annual prices of the main starchy products in the market |
Cotonou Dantokpa |
Parakou |
1994 |
1995 |
1996 |
1994 |
1995 |
1996 |
| Maize Local rice Imported rice Wheat flour Fresh yam Dry yam equiv.* Yam chips Ordinary gari Fine gari Cassava chips |
86 |
106 |
141 |
67 |
87 |
139 |
* |
The price of dry yam equivalent is calculated on a humidity rate of yam chips (13%), taking into consideration losses due to peeling (25%) |
Tab. 2: |
A
comparison of the prices of major foods available in the Cotonou market |
Type of product |
Unit of measure |
Product value |
Prepared food value (FCFA/kg) |
| Yam chips
"Kokoro" Yam chips "Kokoro" Yam flour Fresh yam tubers Cassava chips Cassava chips Cassava flour Gari Imported rice Imported rice Local rice |
bag (± 108 kg) bowl (± 11 kg) tongolo (± 0.8 kg) heap (± 15 kg) bag (± 60 kg) bowl (± 6 kg) tongolo (± 0.95 kg) tongolo (± 0.86 kg) bag (50 kg) tongolo (0.8 kg) tongolo (0.8 kg) |
126 |
33 |
Methodology adopted in the yam chips survey
A survey of the yam chips sector was carried out in 1996 in the three countries on the Gulf of Guinea (Benin, Nigeria and Togo) as part of the "Yam development for urban markets" project financed by the French Co-operation Ministry. These countries were chosen because the production and sale of yam chips seemed to have gained ground there.
The results presented in this paper relate to a food consumption survey conducted in the three countries, using city housewives as respondents. About 200 people were interviewed in the major urban centres of Lomé in Togo, Cotonou in Benin, and five big towns in south-western Nigeria (Lagos, Ibadan, Ife, Abeokuta and Ilorin). The survey was carried out in three phases but this paper only refers to uncompleted data obtained after two visits in April/May, then in September. The last visit was made in January 1997. The first period corresponded to the end of the fresh yam period. The second, on the other hand, was during the new yam season, and the third, when late yam was being introduced into the market.
Major results
The survey first compared the consumption level of amala with that of the other yam-based meals (mainly pounded yam), and also with other starchy foods. It must be noted that amala is by far the main food prepared with yam chip flour.
Comparison of yam consumption level with other starchy foods
Table 3 shows the relatively frequency of consumption of the major starchy foods. The index presented is calculated by weighing the percentage of answers to the question: "Among the following foods, which of the three have you eaten most often in the last week, in decreasing order?". This is not indicative of the quantity consumed, but only makes it possible to establish an order for the foods according to how often they are mentioned.
Tab. 3: |
Consumption level indices* of the major starchy foods. |
Togo |
Benin |
Nigeria |
||||
Survey period |
05/96 |
10/96 |
05/96 |
10/96 |
05/96 |
10/96 |
| Maize Rice Pounded yam Amala Gari Beans Bread |
42 |
42 |
44 |
47 |
9 |
6 |
Weighed indices are calculated
using the formula:
[(% 1st choice x 3) + (% 2nd choice) + (% 3rd choice)]/6
In Cotonou and Lomé, maize is by far the most common starchy food. During the week, consumers alternate this staple food with others: rice and pounded yam in Togo; rice and gari in Benin. In the two countries, amala is merely an alternative to their starchy diet, just as gari is in Lomé, and beans in Cotonou.
In cities in the south-western part of Nigeria, the situation is different. Four main foods were eaten in the week: amala which is most often eaten, (almost 40% of consumers eat it more frequently), rice, gari and beans. Pounded or boiled yam prepared from fresh tubers only occur during the yam harvest when it is most available and the prices are low.
Comparison of the consumption level of amala with pounded yam
Table 4 presents answers to the question: "Which have you eaten more frequently in the past 15 days, amala or pounded yam?"
Tab. 4 |
The
most frequently consumed yam preparation |
Lomé |
Cotonou |
Cities in SW Nigeria |
||||
Visits |
05/96 |
10/96 |
05/96 |
10/96 |
05/96 |
10/96 |
| Amala Pounded yam Both as often Total Number of respondents |
9 |
6 |
87 |
65 |
88 |
72 |
Unlike Lomé where foutou is eaten nine times more frequently than amala, the opposite prevails in the two other countries. In Cotonou and the five towns in south-western Nigeria, the consumption of amala is much higher than that of pounded yam. This is particularly true of the first phase of the survey carried out in May — in other words, when fresh tubers have become scarce and expensive. But it is still quite high in September, during the new yam season when the yam is best suited for the preparation of foutou. Table 5 presents the frequency of amala consumption recorded during the survey.
Tab. 5 |
Frequency of amala consumption (in % of answers). |
Lomé |
Cotonou |
Cities in SW Nigeria |
Visits |
05/96 |
10/96 |
05/96 |
10/96 |
05/96 |
10/96 |
| Every day or
almost Several times a week Occasionally Never TOTAL Number of respondents |
1.0 |
0.5 |
1.4 |
1.0 |
40.9 |
32.7 |
In the cities in south-western Nigeria, the consumption of amala was very frequent since, depending on the period, between 65 and 77% of respondents claim to eat amala every day or more often. In Cotonou the percentage is less but reveals between 14 and 21% regular consumers. In contrast, regular consumers are very few in Lomé.
The living standard, estimated according to the type of house, does not seem to be a determinant factor of yam consumption in Togo or Nigeria. In Benin, the frequency of pounded yam and amala consumption is definitely linked to living standard.
However, obvious differences were noted depending on the geo-cultural origin of consumers. Those from the yam chips production zones were the highest consumers of amala. But it is interesting to note, as presented in table 6, that in a town like Cotonou, the consumption of amala has extended far beyond people of Yoruba origin who were the original consumers.
Tab. 6 |
Frequency of amala consumption according to ethnic group in Benin (for the two phases of the survey in % of answers). |
| Ethnic group | Pounded yam |
Amala |
(numbers) |
Regularly |
Occasion |
Total |
Regularly |
Occasion |
Total |
| Fon (285) Adja (75) Yoruba (48) Others (10) |
7 |
93 |
100 |
16 |
84 |
100 |
Thus Amala would seem to be a vector of yam consumption among people that did not usually eat the tuber.
Amala, eaten for its own meritsReasons given for eating amala are presented in table 7.
Tab. 6 |
Reasons for eating amala (for the two phases of the survey in % of answers). |
Reason given |
Lomé |
Cotonou |
Cities in SW Nigeria |
| I
like it, it tastes good Healthy product Easy to prepare Easily found Cheap By habit or tradition Other Number of respondents |
92 |
74 |
37 |
The total number of answers is higher than
100 because there were several options;
*"other" here corresponds to "as a change from pounded yam"
In Lomé where the consumption of amala is still secondary and far behind pounded yam, the primary reason for consuming it are its eating qualities, and most especially its taste and nutritive value. This response was the same in Benin but there 18% of consumers eat it as a change from pounded yam. In Nigeria, the reasons are more varied. The ease of preparation, its eating and nutritive qualities, and the easy source of supply were the major reasons. The attractive pricing was cited by 23% of the people interviewed. It must be noted that this characteristic was mentioned spontaneously by few people in Lomé and Cotonou.
Far from being a second choice food that is eaten because there is no better alternative, amala would thus appear to be well appreciated for itself. These data are confirmed by the analysis of the answers to the question: "Which do you prefer, Amala or Pounded yam?" On the average during the two visits, it was noted that amala was preferred by 13% of consumers in Lomé, 52% in Cotonou, and 48% in the towns south-west of Nigeria. Generally, these results make it possible to proffer an interpretation for the role of amala. This would appear different according to country.
In Lomé, the consumption of amala is still relatively low because of the strong attachment of consumers to pounded yam. When the fresh tubers are scarce and too expensive, consumers fall back on the other starchy foods. In Cotonou, amala has really penetrated the diet of city dwellers. This makes it possible for real yam eaters to enjoy it all through the year. For those who traditionally do not eat much yam, it is an accessible alternative starchy food.
In the south-western towns of Nigeria, amala is a staple food with a good image, but would appear to be more frequently eaten than the consumers would have us believe. There is no doubt that pounded yam has become less available in urban centres who feel the effects of the scarcity more. Culturally very attached to yam, Nigerians see the yam chips as another way of eating yam when they cannot afford the fresh yam which would have become too expensive.
Conclusion: prospects for development
In several ways therefore, the yam chips sector would appear to be very interesting as regards its ability to diversify the eating habits in urban centres through upgrading local production, and with due regard to the newly developing sedentary farming system. The current processing techniques can be managed by small farmers and do not require much financial investment.
What is left is to be fine-tuned is the technical system which is still limited by the peeling process and the difficulties encountered with drying and storage. Simple improvements from the experience of other countries however seem to be practicable in spite of the low investment capacity of rural producers. The mechanised cutting of the tubers by using the slicers used for cassava (Jeon and Halos, 1994) seems to be a promising development. By reproducing chips of less than one centimetre per section, this equipment will help increase the pace of work and reduce drying period. In the same way, optimising the pre-boiling process with natural fungicides and insecticides as well as sun drying will help improve the quality of the product. The consequences of these technological modifications on the preservation and final quality of the flour are currently being evaluated.
The extension of this technical processing system to other yam producing countries that were not doing this will help reduce the limitations of a sector that is mainly based on fresh tubers. However, this transfer of technology requires the following to succeed:
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adapting the product to the taste of local consumers; |
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confirming the competitiveness of the product with other starchy foods; |
* |
introducing, if not already done, the new material in the cropping system. |
These research activities deserve further study because they are part of the evolutionary trends in the food supply sector to African towns.
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