The main toxic component which occurs in varying
amounts in all parts of the cassava plant is known as linamarin (Philbricket
al.,1977). It often coexists with its methyl homologue called methyl –
linamarian or lotaustralin.Linamarin is a cyanogenic glucoside which is
converted to toxic hydrocyanic acid or prussic acid when it comes into contact
with linamarase, an enzyme that is released when the cells of cassava roots are
ruptured. Otherwise, linamarin is a rather stable compound which is not changed
by boiling the cassava. If it is absorbed from the gut to the blood as the
intact glucoside, it is probably excreted uncharged in the urine without causing
any harm to the organism.
However, ingested
linamarin can liberate cyanide in the gut during digestion. Hydrocyanic acid or
HCN is a volatile compound. It evaporates rapidly in the air at a temperature
of 25.7oC ( Bokanga, 1995) and dissolves readily in water. It may easily be
lost during transport, storage and analysis of specimens. The normal range of
cyanogenic content of cassava tubers falls between 15 and 400mg HCN/kg fresh
weight (Adindu,1973). The concentration varies greatly and also with
environmental and cultural conditions. The concentration of the
cyanogenicglucosides increases from the center of the tuber outwards.
The
objective of this is to enumerate cassava toxicity and detoxification.
2.0 LITERATURE REVIEW
Cassava
(Manihotesculenta) is the staple food of millions of people in the tropics of
both hemispheres, particularly South and Central American , Central and West
African and South – East Asia. It is known as to have been domesticated independently
in central America as well as in south America but introduced from South
America to central America, seems more likely. It was taken to West African
from Brazil by the Portuguese in the sixteenth century.
Cassava
plant is a shrubby, short – lived perennial, growing to a height of 3m or more
with an erect stem, marked by prominent knobby leaf scars. Dwarf cultivars,
rarely exceeding 1m in height, are now available. In a well grown cassava
plant, a cluster of five to ten tubers is produced at the base of the stem (Kochar,
1981).
The leaves tend to be
clustered towards the top of the stem as the lower ones are shed.
Cassava
is essentially a low land tropical crop, although sometimes it is grown as high
as 1830m. It can be grown economically on poor exhausted land (such as in arid
regions) and needs little care. Afriable, fertile, well-drained sandy loam is
considered desirable. Cassava thrives best in full sun and is susceptible to
cold weather and frost. The crop is particularly important in regions where cereals
and potatoes will not grow. It is propagated by stem cuttings (22.5-30cm long)
which are stunk into the soil just before the rainy season. It is often
intercropped with other food crops but may also be planted as a pure stand.
Some varieties mature in as little as seven months,while other may continue to increase in size for up
to four years.
If
kept too long, tuber becomes rather woody and commercially unimportant. The
plants are extremely productive, yielding up to 50t/ha under the best
conditions.The tubers are day out individually for home consumption as they
keep well in the ground. They spoil quickly after harvesting.
A
mature tuber consists of the following three distinct zones, an outer periderm
which may be thick and rough or thin and smooth, varying in colour from white
to pink, red and brown,a thin cortex or ‘rind’ usually white but streaked with
brown in some cultivars and a large white
or cream – coloured pith or core, consisting of a mass of parenchyma in
which are embedded a few xylem strands and lactiferous tubes.
hope you got what you want................
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