Agriculture Reference
In-Depth Information
kernel of some species are variable and in some indigenous fruits they are
comparable with those in exotic and domesticated fruits. For example, the
vitamin C level of
Adansonia digitata
fruits is similar to that of fruits of the same
species grown in Burkina Faso (169-270 mg/100 g; Lamien
et al
., 1996) and
much higher than that of fresh oranges (50-70 mg/100 g) (Williamson, 1975).
Great variation in vitamin C level among locations (Malawi and Tanzania) has
also been observed by Thiong'o
et al
. (2002), who found a large amount of
variation in vitamin C levels (85-319 mg/100 g) for
Sclerocarya birrea
.
However, no significant differences in other food nutrients between trees,
within or between provenances, existed in
S. birrea
. The composition of these
edible parts of plants is thus affected by several factors, such as maturity of the
fruit at harvest, age of tree, soil type, phenotype and agronomic practices. The
daily adult requirement of vitamin C, as reported by Lutham (1997), ranges
from 45 to 80 mg, which implies that only 50 g of the edible part of indigenous
fruits is sufficient to supply the body's daily requirement of the vitamin.
Indigenous fruits could therefore be used as a novel food for malnourished
people and those living with HIV/AIDS in Africa (Rajabiun, 2001).
The mineral composition of pulps (Table 16.5) indicates that potassium
was the most abundant element in
Adansonia digitata
and
Strychnos
cocculoides
. Magnesium and phosphorus were also predominant elements,
while the trace element iron was highest in
Sclerocarya birrea.
Iron is important
for blood formation, hence consumers of these fruits may maintain better
health. The recommended daily amount of iron for children aged 7-10 years is
23 mg. Therefore, consumption of 1 kg of any of the raw fruits per day will give
the child the recommended iron intake (Lutham, 1997). This is dissimilar to
conventional fruits, for which more than 10 kg is required to meet the
recommended daily amount. The amounts of minerals in these fruits per 100 g
are equivalent to the amounts suggested by NRC/NAS (1989) for mineral
mixes to be used for nutrition rehabilitation.
The seed kernel of
Adansonia digitata
is rich in protein (28.7%) and fat
(29.5%); these values (Saka, 1994) are similar to those of leguminous seeds
(Brand
et al
., 1985). This is also the case for
Sclerocarya birrea
, which also has
high protein (28%) and oil (57%) levels (Thiong'o
et al
., 2002). The seed
kernels of
Adansonia digitata
and
Sclerocarya birrea
are also vital sources of
trace elements such as iron, zinc and copper. The quality of the oils from the
seed kernels of
A. digitata
and
S. birrea
is similar to that of groundnut oil, since
the major acids present are palmitic, oleic and linoleic acids (Saka, 1994;
Thiong'o
et al
., 2002). However, unlike groundnut oil,
Adansonia digitata
oil
contains malvalic acid, a toxic cyclopropanoid fatty acid, which limits its use for
human consumption, but which can be removed by hydrogenation. In rural
areas of the Nguru, Usambara and Ulugulu mountains in Tanzania, the seeds of
Allanblackia stuhlmanii
are used to extract cooking oil and their fat content is
68.2% (Ndabikunze
et al
., 2000). This wild seed kernel contains more fat than
coconut (36%), almonds (53.5%) and groundnuts (49%) (Ndabikunze
et al
.,
2000). This clearly indicates the potential for commercial cooking oil production
from indigenous fruit seed kernels.
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