1.2.8 Other oil-yielding plants
The sheanut or karite, Vitellaria paradoxa (syn.: Butyrospermum
parkii), is a wild-growing tree in the countries south of the Sahel zone. The
tree is relatively small, growing to a height of some 12 metres, having a thick
trunk and a number of spreading branches which form a dense crown. It bears
fruit after 10 to 15 years, reaching full bearing capacity at 20 to 25 years.
From Senegal to Sudan, the fruit, which requires 4 to 6 months
to mature, is locally of substantial economic importance in particular for rural
women who collect the nuts and process them to a butter-like edible substance.
Average yield per tree is 15 to 20 kg of fresh fruit, with one third of the
trees being productive each year. 50 kg of fresh nuts give 20 kg dry kernels
which yield about 4 kg of shea butter.
The kernel of the nut contains 32 to 54 % fat. In international
trade, shea butter serves as a cheaper substitute for cocoa butter and is in
high demand when prices for the latter are up. It is also valuable for the
cosmetic industry. With an estimated total production (collected nuts) of 500000
tons per year, Nigeria, Ghana, Ivory Coast and to a lesser extent, other
countries in West Africa, are reported to export altogether about 30 000 tons.
Actual production and even export figures, however, are
difficult to verify. In Mali, for example, production of kernels in the season
1985/86 is estimated to be 44000 tons, of which 10200 tons were officially
exported. Inofficially, an estimated additional 16000 tons have left the country
for unknown destinations.
Cotton, Gossypium spp., is basically a textile plant, which is
mainly cultivated for its hair or lint (9.5 to 20 mm long) on the stem and
leaves. Apart from the commercial value of the fibre, however, the seeds contain
about 25 % oil thus making cotton the third most important oil crop. Of
additional value is the protein-rich (40 %) oilseed cake, which gives a good
protein supplement for cattle. The oilcake, however, can contain free gossypol,
a pigment sometimes found in cottonseed. In this case, the use of the cake is
limited to feeding to non-ruminants in small quantities.
World production of the seeds has exceeded 30 million tons in
recent years, and of cottonseed oil between 3 and 4 million tons (see Tables I
and 2). Major producers of cottonseeds are China, USSR and the USA. Although the
plant originates from semi-arid zones in Africa, the continent as a whole
(mainly Egypt and Sudan) only contributes 7 % to world production. World trade
in cottonseed oil is dominated by the USA and Brazil. Due to the relatively low
oil content of the seeds, solvent extraction is generally applied as a larger
industrial operation; small-scale equipment does not appear to provide economic
Linseed, Linum usitatissimum L., is also mainly cultivated for
its fibre, but is in multiple use as a spice and an oil yielding plant. World
production in linseeds has considerably decreased over the last two decades and
currently stands at about 2.5 million tons annually. The major producers are
Canada and Argentina; production in Africa is negligible. Linseed oil is used
mainly for technical purposes (paints) and faces heavy competition from other
vegetable oils and in particular synthetic products. The market for the oil is
more or less taken by Argentina (71 %) and the Federal Republic of Germany (17
%). Small-scale extraction is done in India.
Maize (Corn in American diction), Zeamays L., is basically a
starch plant, but the oil content of the germ is also used on a commercial
scale. The plant originates from Central and South America from where it began
to spread to almost all parts of the world. Today, the USA is the largest
producer, both American sub-continents together still contributing the majority
(60 %) to the total world production. Maize oil is rather a minor byproduct of
the maize starch manufacturing industry and is extracted on an industrial scale.
World trade in maize oil amounts to about 300 000 tons annually, largest
exporters being Europe and the USA. Africa accounts for net imports of some 10
000 tons a year.
Safflower, Carthamus tinctorius, originates from the eastern
Mediterranean and the Persian Gulf and was first cultivated for the orange dye
obtained from the florets. The seeds of modern varieties, however, contain 36 %
to 48 % oil with good qualities for human consumption; a fact which now
constitutes the main purpose for the cultivation of the plant whose seeds are
suitable for small-scale processing.
The plant is a highly branched, herbeceous annual, varying in
height from 30 to 150 cm and generally has yellow flowers. The fruit resembles a
small, slightly rectangular sunflower seed, but with a thicker, more fibrous
hull. It gives best yields (but with I ton/ha still low) in semiarid climates.
Due to its fairly good drought and salt resistance, safflower is suitable for
areas where other oil seeds are difficult to grow.
World production of safflower seed increased sharply in the
1960's but has since remained static at just below I million tons a year, with
India accounting for more than half of the total. Safflower is still considered
a typical small-holder crop and is mostly processed and consumed locally; for
large plantations, as those in Mexico until recently, other oil seeds,
particularly hybrid sunflower, appear to be more profitable.
Castor, Ricinus communis, is indigenous to eastern Africa, most
likely originating in Ethiopia, but has a contemporary world-wide distribution
in the warmer regions. Originally a tree with heights up to 10 m, most
mechanically cultivated varieties today are short-lived dwarf annuals and only
60 to 120 cm high. Castor plants also grow wild in many countries and production
could be substantially increased if incentives were sufficient. This is
particularly so in eastern Africa, from the southern Sudan to southern Tanzania,
where there are extensive areas with wild species.
Castor seeds (or beans") almost exclusively originate from
the developing countries, the major producers being China and Argentina.
Although Africa does not play a major role in official statistics of world
production (3 %), castor seeds might well be of greater economic significance in
the local context. In world trade of castor oil, Brazil and India clearly
dominate the supply side with a combined market share of over 90 %; largest
importing region is Western Europe.
A large proportion of castor seeds on local markets in less
developed regions is obtained from wild or semi-cultivated plants. At least in
Africa, systematic cultivation of pure stands of castor by peasant farmers is
the exception. More often castor is interplanted with other crops, sown along
borders of fields, planted in areas unsuitable for other crops or merely
protected when found growing naturally. In a cultivated stage, yields per ha are
a mere 0.5 to I ton. The seeds, however, have a high oil content of 42 % to 56 %
and are suited for small-scale processing methods. The oil is used for a variety
of technical purposes.
Other oil yielding plants suitable for small-scale processing,
which, for reasons of space cannot be dealt with in detail, include:
- Physic Nut (Purgier), Jatropha curcas, the oil of which is
mostly used for soap and might be economically used as a fuel on the Cape Verde
- Niger Seed, Guizotia abyssinica, which is produced in India and
Ethiopia and gives a good edible oil,
- Babassu, Orbignya oliefera,
originating from Brazil with nuts containing 2to 8 kernels with 60 % oil similar
to coconut oil,
- Cohune, Orbignya cohune, growing in Central America, the
nuts containing a kernel with 60 % oil comparable to coconut oil,
Melia azadirachta L. (A-adirachta indica), growing in Africa, SE-Asia and India,
with seeds containing 45 % oil, which is mainly used for soap and medical
- a large number of wild growing oil yielding plants of local