0604-A2

Food quality of indigenous fruits and vegetables from western and central Africa: Opportunities for coping with the HIV/AIDS threat, rainforest biodiversity conservation and livelihood improvement

E. Kengni, C.M.F. Mbofung, M.F. Tchouanguep, Z. Tchoundjeu and R.R.B. Leakey ¹

Abstract

Suboptimal utilization of forest food products and the growing HIV/AIDS threat to agriculture and food and nutritional security in West and Central Africa add further burdens to efforts towards poverty alleviation and mitigation of deforestation. To resolve this complex problem, linkages of these factors with value-added processing and other food value options of non-timber forest products are essential. This might constitute an incentive for subsistence farmers to reduce the intensity of slash-and-burn agriculture currently still preponderant in the subregion.

Introduction

The sub-region of Humid Western and Central Africa is the second largest biodiversity reservoir of the world after the Amazon. However, the human development indicators show that the annual population growth rate is 2.5 percent per annum, infant mortality under 5 years 410 per one thousand, GDP per capita 534 US$ against the Africa's average of US$708, and the percentage of adult living with HIV/AIDS 4-15 percent (UNAIDS, 2000). Annual deforestation rate is 0.8-1.4 percent against 0.02 - 0.04 percent annual reforestation rate. Rural poverty accounts for 90 percent of total poverty and about 80 percent of poor still depend on agriculture for their livelihood (Dykstra et al. 1996).

Main land use systems are forest based cash crop, root crop and cereal-root crop mixed farming systems. They require high labor intensity and are closely related to slash and burn agriculture (FAO & World Bank 2001). However, at the margins of the forests, multi-strata agroforestry systems are increasingly being developed based on cropping cash and food crops with economic indigenous fruit and medicinal trees and shrubs. They have considerable genetic variability often ignorantly maintained by farmers by the means of their indigenous knowledge (Anonymous 2001). Their improvement is needed for full adoption and impact.

Continuation to pay attention to sustainability and overcoming long-term vulnerability in order to break the vicious cycle between food insecurity and HIVAIDS vulnerability may be a solution to cope with the pandemic threat at rural level. This approach can be efficient if based on good food source crops that require less labor intensive was advocated as a long-term measure to cope with the pandemic threat (UNAIDS 2001). In agreement with these statements, the exploitation of fresh fruits of Dacryodes edulis (safou/African plum), dried kernels and cake of Irvingia gabonensis and I. wombolu (ogbono/dikanut), fruit flesh of I. gabonensis (bush mango), dried kernels of Ricinodendron heudelotii (njansan) and fresh leaves of Gnetum africanum (eru) in Humid West Africa has become the main source of food cash incomes, employment and enhanced livelihood for subsistence farmers. As such they should be carefully screened for their intrinsic and extrinsic values with potential to increase opportunities for postharvest processing and the use in the food industries (Shannon 1996). Without these measures, the above vicious cycle of HIV/AIDS and malnutrition will not be broken.

This article makes case for a holistic approach of improving food quality of NTFPs to cope with the HIV/AIDS threat for short and long-term agricultural development, commercial biodiversity development and enhanced livelihood of rural poor in Western and Central Africa.

HIV/AIDS, NTFPS and nutrition

The challenge of HIV/AIDS on poor rural and urban populations can be seen in two perspectives namely biological and socioeconomic. Between these two components, non-timber forest food products and the resulting diets have a crucial role to play in order to provide the body with all the necessary nutrients needed for its full development. Their potential to provide cash incomes and employment is an asset. In 1995 for example 1512 KG of NTFPs were trade in Cameroon for a value of 1,400,000 US$ (Ruiz-Perez et al 1998). A price received by one grower per annum is estimated at US$ 80 for D. edulis. Apart from their food uses, the barks of D. edulis, I. gabonensis and R. heudelotii are used as medicines to treat yellow fever, dysentery and diarrhea (Ayuk et al 1999a and b), thus their great contribution of the health care of rural populations.

The interactions between the biological and socioeconomic consequences of the HIV/AIDS pandemic have direct implications at individual, household and community levels. HIV infected individuals have decreased absorption, excessive urinary losses and low blood concentrations of vitamins A, B1, B2, B6, B12, C, E as well as folate, bet-carotene, selenium, zinc and magnesium (Friis and Michaelsen 1998). This situation weakens the immune system and gives way to opportunistic diseases. The body response to invading pathogens is in the form of pro-oxidant cytokines leading to increased utilization of anti-oxidants such as vitamins A, C, E and Beta-carotenes and the resulting cells, proteins and enzymes damage (Pivoz and Preble 2000). However, this situation can be mitigated using rich diets based on local food materials. For example, D. edulis fruit pulp and R. heudelotii kernel fats are rich in unsaturated fatty (75 g and 157g iodine/100g of fat respectively). The iodine value of R. heudelotii fats is higher than the value found in cotton and soybean seeds. Also, the density of energy in Irvingia spp. (Irvingia) kernels is higher than that found in oilseeds such as peanuts, cowpeas and soybeans Kengni (2002).

Chemical Composition, nutritional value and genetic diversity

Data on the chemical composition of NTFPs in West Africa exist at the species level (Leakey, 1999). Since the number of staple crop per household is likely to be reduced in HIV/AIDA affected households, the rest of the community will need to fill the gap by producing not just the right quantity, but also will supply AIDS infected persons with part of their produce and meet demands relating to aspects of diversity, external and internal qualities, above all for consistency in supply. Information on individual nutrients is rare. Essential in the nutritional potential of NTFPs is the digestibility of their nutrients in the intestinal tract. The absorption of these nutrients in the intestinal lumen varies depending of nutrient source, type and treatment applied. The defatted kernels of Irvingia spp. and D. edulis pulp have up to 25 % crude proteins and protein digestibility to 36.5% and 77.0% (Kengni 2002). There is a real need for further assessment of the nutrient availability in these species and others, which form the basis for any food quality improvement. The most important amino acids of these two foods are tryptophan, valine, isoleune, threonine, leucine with concentrations comparable to those found in hen's egg. They are even higher in the case of R. heudelotii kernels and Gnetum africanum.

Table 1: Chemical composition and nutritional value of major forest foods from Western and Central Africa.

Results of the minerals composition of fruits from both species have shown that in Nigeria they are rich in macrominerals while in Cameroon they are particularly rich in microminerals elements. Levels of Fe, Zn, Mn, Mg and Cu are particularly important because most frequently they are those involved in micronutrient malnutrition. Moreover, vitamin A values in Table 1 are particularly higher compared to those of vitamin C. This indicates that their daily consumption is considerable since substantial quantities of these fruits are consumed daily in Humid Western and Central Africa. The considerable contents of foods in anti-oxidants such as vitamins A and C as well as Zn and Mg may help reduce the metabolic alterations in HIV-infected individuals while those of energy can prevent protein-energy malnutrition and help reduce disease progression.

Storage and processing

More communities around the world are taking charge of their local environmental quality and quality of life issues. It is always accepted that the commercialization of forest foods in the sub-region makes significant contribution to household budgets. However, a recent study has indicated that there is lack of storage and processing knowledge and skills available for smallholder farmers (Schreckenberg et al 2002). Storage and processing are great determinants of extended shelf life and value added in agricultural outputs (FAO 1997). They also help to improve the nutritional value of raw foods by rending most of the antinutritional factors, metabolic enzymes and microbes inactive.

Currently, apart from Irvingia spp. kernels for which farmers manage to process the kernels into a paste called cake or ogbono, other fruits and vegetables experience high postharvest losses being more than 50 % for D. edulis fruits. However, recently a spread has been made from the soft pulp of D. edulis and no significant difference was observed between its use in bread eating and that of both chocolate and margarine (Kengni et al. unpublished) (Table 2). Most of these species produce seeds that are used to flavor and thicken soups but information on the water absorption capacity, oil absorption capacity, emulsification value, foam stability and nitrogen solubility is scanty (Kengni et al. 2000a). The latter characteristics constitute the basis use of food as ingredients in the food industry and help communities realize long-term continuous benefits of their natural resource base use and preservation.

Table 2: Mean of sensory attributes of safou spread compared to chocolate and margarine

Product description and consumer needs

Given the knowledge acquired by consumers of non-local foods, research efforts need to be more than double to add quality to these foods in order to make them well known, expand their market and sustain their production. At present the bulk of consumers are natives of the sub-region. But the expansion of markets and development of new ones suggests meeting traditional and newly recruited consumers from different markets. Ladipo (1998) has called for development of quality standards that can guide the grading of forest products and latter in the process the harmonization of their trade. In this respect, Kengni et al (2000b) have developed a list of sensory terms that describe the cooked pulp of D. edulis and used it to discriminate different varieties of fruits collected at the markets based on fruit sizes and colors (Table 3)(Kengni et al 2001). Because low returns constitute a trade off and sources of vulnerability this study was also extended to the identification of the market qualities that guide consumer choices thus the prices paid.

Table 3: Major sensory attributes of major marketed D. edulis fruit colors in Yaounde (Cameroon) markets

Values sharing the same letter superscript in the same column are not significantly different (p > 0.05)

Impact on the domestication of indigenous fruit trees and shrubs

Domestication refers to accelerated and human induced evolution to bring species into wider cultivation through a farmer-driven and often a market-led. It involves the identification, production, management and adoption of desirable germplam with the aim to improve the livelihood of rural and peri-urban communities through cultivation, harvesting, consumption and sales of NTFPS derived primarily from trees (ICRAF 1997). With the emergence of HIV/AIDS in rural areas of western and Central Africa, the link between fruits and vegetables cultivation and consumption on one hand and the nutritional status of household members vis-à-vis the epidemic on the other hand. This important long-term option can help rural communities overcome labor shortages since their production is not labor intensive. According to Arnold (1990), the result of a study in Nigeria shows that when labor is the household's major farm input, returns to labor in agroforestry systems are four to eight times greater than those in monocropped fields. However, since domestication goes hand in hand with commercialization, it would be important to explore ways available to develop markets of NTFPs to help HIV/AIDS affected families have minimum incomes to pay either drugs or buy foods to meet their dietary and other basic needs (Barany et al 2001). The provision of good nutrition and other benefits of these indigenous food products depend upon policies targeted to boost their food value.

Acknowledgements

This work was supported by the African Network for Agroforestry Education (ANAFE).

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¹ IRAD/ICRAF Project; POB 2067 (Messa) Yaounde, Cameroon. [email protected]