Most non-wood forest products are still collected and marketed informally. This does not allow for adequate attention to be paid to quality. Quality can mean different things to both producers and users and is usually tied to remuneration (i.e. attaining a good price) so farmers try to achieve as high a quality as possible to benefit from higher financial returns. Strict rules on quality determination are not new to West and Central African farmers who have grown cash crops such as coffee and cocoa for many decades for overseas processors and consumers.
Although many non-wood forest products of the native forests in this sub-region are still restricted to small local trade, some products have reached 'far national' and international markets. Irvingia gabonensis and Irvingia wombolu are the two Irvingia species that produce kernels eaten in West and Central Africa (Harris, 1996). The fruit of Irvingia gabonensis has a sweet mesocarp and it is eaten fresh, while that of Irvingia wombolu is sour and is not consumed locally. The edible kernels from both are used for culinary purposes and are traded widely; enough to be quoted on the weekly commodity lists in Nigeria. Ogbono is used as soup thickener in West and Central Africa and also to make dika cake in Central Africa, particularly in Gabon. Other uses of the kernels, such as their pharmaceutical grade fat (oil), are also being developed. A grading of quality classes is suggested for ogbono (kernels) ranging from grades A to D (with A being the best quality). The development of this quality classification has been dictated by the response of various farmers, wholesalers and consumers in the South of Nigeria where ogbono is consumed traditionally and extensively. The present effort is to provide at least a starting point in the process of quality standardisation in this commodity to increase revenues for both traders and producers.
Key words: Irvingia gabonensis, I. wombolu, kernels, quality, trade
Most non-timber forest products in West and Central Africa are still marketed and sold on an informal basis often in forest fringe markets, and in local village market places from where users purchase them for direct use. In the case of more 'advanced' products however, wholesalers purchase these NWFPs in village markets from where they are cleaned, packaged and transported to urban markets. Some products are also traded further and supply growing international markets.
Ndoye et al., (1997) reported substantial markets for a wide variety of non-wood forest products. This study provided sale prices and evidence of price variation as influenced by season or product seasonality within the Cameroon area. However, few product quality standards for the enhancement of market opportunities have been implemented to date though the development of practical guidelines has considerable potential for the enhancement of product values and hence the income of the gatherer or producer.
A few examples do exist though. In the case of kola (Cola nitida and C. acuminata) informal rules and regulations have been applied in the marketing of kola nuts for many years. For trans-savannah trade within West Africa in particular, nuts are sorted according to colour and size and each of these classes command their own prices according to quality. For a few of the indigenous and more recent wild fruit crops, quality control is being exerted by informal associations or co-operative unions. A good example is the informal Dacryodes edulis export market in Douala, Cameroon. Export of the bush plum from Cameroon to Gabon follows strict gradings and the price varies according to quality.
However, for the marketer and consumer, the term quality is subjective. To the producer and wholesaler it could mean those kernels that secure a maximum price in the market at a particular time of the season. To the consumer quality could mean presentability and end product quality, i.e. soup drawability. Quality to this person could then be defined in terms of end-use.
For Irvingia kernels there are some general aspects of quality that can be considered and that are shared by both the marketer and consumer. These include size of kernel, thickness of kernel, colour, maturity and extent of blemishes or damage. Ladipo (1994) after a preference survey, reported that important factors in quality for the consumer in the case of the eating and cooking of Irvingia are:
· Appearance, including kernel size, colour and shape;
· Condition (pests) and absence of defects (mechanical damage, etc);
· Oil content;
· Flavour (sliminess of kernel after processing or cooking); and
· Level of adulteration of kernels (the mixing of I. gabonensis and I. wombolu kernels).
The market for ogbono products is said to be worth some US$ 50 million (ICRAF, 1975). Ladipo and Boland (1994) reported extensive local and regional trade within Nigeria and between countries in West and Central Africa such as Nigeria, Gabon and Cameroon. Processed kernels of Irvingia are also transported from Africa to the UK and the USA, particularly to areas where African immigrants abound in large numbers. They are also sold in Paris and Brussels (Tabuna, this volume). Produce marketing in the 'raw' ungraded state attracts less financial returns. This is why a process of grading needs to be introduced for these NWFPs so as to enhance their value and the income of their producers. The various factors for consideration are presented below. Further uses of ogbono may increase this market yet further. For example it is suggested that the kernel oil could be of value in the binding of pharmaceuticals (Okafor, pers. comm.) and have considerable industrial applications.
This is the cultural or field aspect of quality control. In the case of planted trees, this essentially involves the use of good planting materials and the application of good tree management techniques which will allow the full potential of the genotypes planted. It also involves good disease and pest control management. In the case of wild trees, the source of which constitutes 99% of produce presently marketed in West and Central Africa, it is the selective collection of fruits that matters so the kernels extracted can be of good quality.
This comes into play post-harvest after the fruits have been collected. Post-harvest quality depends substantially on farmer practice and will include the handling of the produce even from kernel extraction. Factors include:
· Harvest of fruits
· Extraction of kernels
· Drying of kernels
· Sorting of kernels
· Storage and packaging
Fruit harvesting has to be undertaken at the optimum time to prevent the harvest of immature fruits. The extraction of the kernels entails the fruits being split open using machetes (when the fruits are fresh) or with truncheons or hard stones when they are dry or fermented fruits. The seed shell splits open through the longitudinal line of weakness, exposing the kernels wrapped in a dark brown testa. Extracted kernels are further dried for storage or for direct sale in units of 5, 10 or 25 kg sacks on the wholesale market. Methods of extraction have been reported to differ between countries. The kernels of Irvingia in South West Nigeria are usually extracted in the fresh state, then dried before storage and sale, whereas dry stage extraction, which requires very little additional drying, is the preferred means of extraction practised in Cameroon.
Drying of kernels is very important. Without this, stored kernels become discoloured and prone to fungal attack and this is a major determinant of quality. Post-harvest attack by insect pests can seriously affect products' market acceptability. Ashiru (1997) has isolated and described the insect pest responsible for the damage to Irvingia kernels in storage. Aside from pest and disease susceptibility there are also many environmental factors which can affect the rate of quality decline in ogbono. High humidity and also high temperature decreases colour quality as whitish cream kernels turn brownish or dark tan.
The sliminess of the dika cake (a preparation of hard-pressed kernels that resembles a cake) and ogbono soup is a vital traditional attribute. Kernels of Irvingia wombolu are well known for their high slimy consistency, while the kernels of Irvingia gabonensis are less slimy. Because of the abundance of I. gabonensis, it is common to encounter mixing of the two types and it is vital that the two species are separated. In general, a higher grade can be attributed to I. wombolu since it is slimier and preferred.
With the above parameters to consider for quality determination in Irvingia the quality variables can be numerous. They include the following:
· Visual quality: If Irvingia is harvested in the immature state, extracted kernels are greenish, thin and shrunken. Kernel colour after drying should be whitish-cream on the inside and dark brown on the outside. Colour must be uniform on the kernel without being patchy.
· Kernel size: Generally larger, uniform kernels are preferred.
· Kernel thickness: This refers to the wholeness of kernels. Those damaged during extraction will break easily, especially at the drying stage, while immature kernels are prone to shrinkage and are often irregular in shape.
· Level of sliminess: This trait is vital for local acceptance, since the product (kernels) is use-oriented with consumers preferring a slimy consistency to the end product. To test for sliminess kernels should be ground into a paste, wetted with a little water and then rubbed between the fingers. The level of sliminess of the sample can then be determined. It can be classified as (i) high, (ii) average or (iii) low, depending on the observations obtained.
· Pest damage to kernel: Storage insects are known to cause significant damage to kernels (Ashiru 1996). These insects bore through kernels thus damaging them. Kernel infestation can be classified as having suffered (i) severe damage, (ii) average, (iii) low or (iv) no insect damage at all.
Table 1. Irvingia kernel parameters and quality classes.
Grade of sample |
Parameters |
|
A |
· No debris in kernel mass · Kernels dry (8% moisture content) · Cream in colour · Kernel is whole, unbroken · Kernel powder is very slimy · No pest damage · No fungal damage · Kernel is large and thick |
|
B |
· Little debris in kernel mass · Kernels dry (8-10% moisture content) · Cream / yellow in colour · Average kernel size · Kernel powder averagely slimy · No pest damage · No fungal damage · Kernel is averagely large and thin |
|
C |
· High debris content in kernel mass · Kernels dry (+10% moisture content) · Darkish brown in colour · Kernel size variable · Kernel powder not particularly slimy · Slight pest infestation · Slight fungal infestation · Kernel small and thin |
|
D |
· Very high debris content in kernel mass · Kernels inadequately dried · Blackish (mottled) or green (immature) in colour · Kernel powder not at all slimy · Kernel broken into pieces · Heavy pest infestation · Heavy fungal infestation · Kernel is small and thin |
· Fungal damage to kernel: Fungal infection causes discoloration in Irvingia kernels. This often results from improper handling during extraction due to high humidity and inadequate drying which will encourage fungal growth. Colour changes can vary from brown to black depending on the stage of infection and this could also vary from (i) extensive (more than half of kernel discoloured) to (ii) average (less than half of kernel discoloured) to (iii) low and (iv) no discoloration at all.
· Level of kernel moisture content: More effective drying helps prevent pest and disease attack.
· Mechanical damage (breakage) to kernels: Damage to kernels often occurs during extraction and damaged kernels reduce kernel quality significantly.
With the above considerations, it is clear that appropriate variations in price must be applied to justify the efforts of a farmer or wholesaler required to maintain the high quality prescribed. For example, a 50% price difference should be specified between the specific grades A and B, while a 10% difference should be specified for grades C and D compared to B. With this, D class is discouraged as only 30% of the price of A will be obtained. For further elaboration, see Table 1.
The impact of the international cocoa and coffee boards on the quality maintenance of these export products is well recorded. However, for NWFPs and other "minor" products, the need for local farmer co-operatives is critical, and I would suggest that Irvingia Farmers Associations (IFA) and Minor Crops Marketing Boards should be established in West and Central African countries along the same lines as the cocoa and coffee boards and the Dacryodes edulis trading system. This will conform with the European Union (EU) initiative on the enhancement of the tropical fruit trade to Europe which has resulted in the promotion of a number of forest fruits (otherwise considered "minor forest products") with substantial economic returns to many developing countries and the producers concerned, small-scale farmers.
The present market spread of Irvingia kernels has been reported by Ladipo and Boland (1994) and is growing steadily. As more uses are promoted for Irvingia and its products, sales of ogbono will increase substantially in the near future. If the development of the resource take place under the guidelines outlined above, the case of Irvingia kernels could perhaps provide a model for the development of other NWFPs of West and Central Africa.
Ashiru, M.A. 1996. Pest damage of Irvingia kernels in storage. In D. O. Ladipo & D. Boland (Eds) Proceedings of the International Workshop on Irvingia in West Africa. International Centre for Research in Agroforestry (ICRAF) ,Nairobi, Kenya.
Harris, D.J. 1996. A revision of the Irvingiaceae in Africa. Bull. Jard. Bot. Belg. 65:143-196.
Ladipo, D.O. 1994. Farmer preference survey on Irvingia gabonensis in Southern Nigeria. Unpubl. report.
Ladipo, D.O. 1997. Marketing and post harvest constraints of traditional vegetables in sub-Saharan Africa. Paper presented at NRI-IPGRI International Workshop on African Indigenous Vegetables, Limbe, Cameroon.
Ladipo, D.O. & D.J. Boland. 1994. Trade in Irvingia kernels. In D. O. Ladipo & D. Boland (eds.): Proceedings of the international workshop on Irvingia in West Africa. International Centre for Research in Agroforestry (ICRAF) Nairobi, Kenya.
Ladipo, D.O., J.M. Fondoun & N. Ganga. 1996. Domestication of the bush mango (Irvingia spp): Some exploitable intraspecific variations in West and Central Africa. In Proceedings of the FAO/ICRAF International Conference on the Domestication and Commercialization of non-timber forest products in Agroforestry systems ,pp 193-206.
Ndoye, O. M. Ruiz-Perez & A. Eyebe (1997). The markets of Non-timber Forest products in the humid Forest Zone of Cameroon. Rural Development Forestry Network. Paper No 22c ODI, London, UK.
