The little-understood indigenous African fruit trees
What do ‘monkey bread’, desert date, and jujube have in common?
For one, they are fruit trees native to sub-Saharan Africa, mostly known only in their immediate localities. They are also united by a severe shortage of research data on their nutritional composition. As researchers from the Food and Agriculture Organization of the United Nations (FAO) and World Agroforestry Centre (ICRAF) discovered, information on the composition of these, and seven similar indigenous African tree species, is “limited and fragmented.”
Yet as Ramni Jamnadass, leader of the Global Research Priority on Quality Trees at the World Agroforestry Centre (ICRAF) notes, this knowledge is needed in agroforestry research. “When selecting fruit tree species to domesticate for nutritional security in Africa, you base your decisions on nutrition data, as well as farmers’ local knowledge,” she says. Jamnadass is a co-author of a recent paper on the nutrient compositions of indigenous African trees fruits published in the Journal of the Science of Food and Agriculture.
The researchers selected ten indigenous fruit trees from sub-Saharan Africa, and set out to gather data on the nutrient composition of their fruits, as published in research articles. They planned to evaluate the nutritional differences among and within the different species, and to add these data to the FAO/INFOODS food composition database for biodiversity. The tree species selected were: baobab/monkey bread (Adansonia digitata), desert date (Balanites aegyptiaca), bush butter tree/African pear (Dacryodes edulis), wild mango/African mango (Irvingia gabonensis), marula (Sclerocarya birrea), black plum/water berry (Syzygium guineense), tamarind (Tamarindus indica), wild loquat (Uapaca kirkiana), African black plum/chocolate berry (Vitex doniana) and jujube/ber fruit (Ziziphus mauritiana).
Baobab and African pear had the most research data available online, but the other eight had very little information, with African black plum, wild loquat, and black plum at the tail end of data availability.
The data found in the scientific literature presented several problems. For example, lack of units/denominators, missing values, or imprecise food descriptions meant that many entries had to be excluded from the analysis. Sometimes, after being standardized (per 100 g edible portion) to allow comparison, the resultant data were implausible vis-à-vis international food composition tables, and had to be omitted. According to the article, out of the over 100 papers found, 41 had to be excluded because they could not be standardized or their data quality was wanting.
The researchers found, too, that most of the information in the articles was for macronutrients (e.g. protein, fat, carbohydrates) and minerals; very little was on vitamins, except Vitamin C.
Despite these limitations, two comparison tables on the nutritional content of the ten tree fruits were drawn up. Baobab fruit, overall, had the lowest water content but the highest energy, available carbohydrate, fibre, ash, vitamin C, calcium, magnesium and potassium contents. This nutritious fruit tipped the scales at 273 mg of Vitamin C per 100 g on average in the pulp, followed by marula fruit, at 167 mg per 100 g on average.
The article’s lead author, nutrition specialist Barbara Stadlmayr, highlights that in addition to their high nutritional value, these indigenous fruits have another important advantage: they produce even when staple crops fail (e.g. during droughts), and in this way bridge the ‘hunger gap’ during times of food shortage.
Indigenous fruit trees can also serve as a source of income for farmers to improve livelihoods. Participatory Domestication enables farmers to grow these trees widely in agroforestry systems, and multiplies these gains. For instance, bush mango (Irvingia gabonensis) has been domesticated through an effort by
ICRAF scientists working with research partners and communities in West Africa. The bush mango today is in high demand locally and beyond, and contributes to nutrition and livelihood security. A recent review on non-timber forest products in Cameroon reported that over 8 million US dollars is generated annually from the sale of Irvingia spp.
“We could cut the chain of poverty and transform lives in Africa by working seriously on indigenous fruit trees,” Zac Tchoundjeu, ICRAF senior scientist and tree domestication expert, told at a recent ICRAF side event at the Africa Agriculture Science Week (AASW6).
The population and diversity of these trees is said to be dwindling in many parts of the continent, and researchers expect that this loss will probably be accelerated in the near future as a result of climate change. “This biodiversity loss is expected to harm food and nutrition security, particularly in developing countries and emerging economies,” says Jamnadass.
There is a need, and an urgency, to gather high-quality data on a wider spectrum of components of the selected indigenous fruits in sub-Saharan Africa,” says Stadlmayr.
The authors emphasise that attention should be given to proper data sampling and handling, and the accuracy and precision of analytical methods used. This will allow the data to be comparable, and the methodologies replicable. Moreover, “differences related to geographical regions should be described in more detail and differences according to tree genetics investigated,” they recommend. The International Network of Food Data Systems (INFOODS) provides international guidelines and standards for this type of research (including food and component nomenclature; data interchange; compilation; data checks; conversions; sampling; and data quality). Recommendations regarding preferred methods and available technology are discussed in detail in the book: Food Composition Data: Production, Management and Use, by Greenfield And Southgate (2003).
Download full Open Access article: Nutrient composition of selected indigenous fruits from sub-Saharan Africa by Barbara Stadlmayr, U Ruth Charrondière, Sandra Eisenwagen, Ramni Jamnadass, and Katja Kehlenbeck
Related resources and stories
- International Network of Food Data Systems (INFOODS)
- A bit of baobab a day keeps the doctor away: wild fruits help solve Africa’s malnutrition crisis
- The fruits of success: a programme to domesticate West and Central Africa s wild fruit trees is raising incomes, improving health and stimulating the rural economy
- Fruit tree planting is no monkey business
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- On the forest’s margins: bringing the benefits of trees from the wild into the farm
- Trees and food security in Africa; what’s the link?
Photos of Indigenous African Tree Fruits and their products at: Living with the Trees of Life Facebook Page