Nature of cassava
The plant
The cassava plant is a perennial that grows under cultivation
to a height of about 2-4 meters. The large, palmate leaves ordinarily
have five to seven lobes borne on a long slender petiole, and
grow only toward the end of the branches. As the plant grows,
the main stem forks, usually into three branches which then
divide similarly. The roots or tubers radiate from the stem
just below the surface of the ground. Feeder roots grow vertically
from the stem, and storage roots penetrate the soil to a depth
of 50-100cm. The capacity of the cassava plant to obtain nourishment
from some distance below the surface may help to explain its
growth in inferior soils.
Male and female flowers arranged in loose plumes are produced
on the same plant. The triangular-shaped fruit each contain
three seeds. The number of tuberous roots and their dimensions
vary greatly among the different varieties. The roots may reach
a size of 30-120 cm long and 4-15 cm in diameter, and a weight
of 1-8 kg or more.
Clusters of root of the Bogor variety, ripe for harvesting,
are shown in Figure 3. A cross section of the root is given
in Figure 4. The peel consists of an outer and an inner part,
the former comprising a layer of cork cells and the phellogen.
The cork layer, generally dark-colored, can be removed by brushing
in water, as is done in the washers of large factories. The
inner part of the peel contains the phelloderm and the phloem,
which separates the peel from the body of the root. The texture
of the transition layer makes possible an easy loosening of
the whole peel from the central part, thus facilitating the
peeling of the roots.
The cork layer represents 0.5-2 percent of the weight of the
whole root, whereas the inner part of the peel accounts for
about 8-15 percent. In ripe roots this is generally about 2-3mm
thick. The starch content of the peel is only about half that
of the core. The peel is much firmer, hindering a smooth rasping
by primitive raspers; small factories prefer to peel the roots
before working them up. The loss of starch incurred by rejecting
the peel, however, is not acceptable to the larger factories,
which remove only the cork layer.
| Nature
of cassava |
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