vegetables are valuable
sources of nutrients
especially in rural
areas where they contribute substantially
to protein, minerals,
vitamins, fibre and
other beneficial nutrients.
Corchorus olitorius that is used
as soup condiments
in Nigeria was subjected to cooking
in order to
evaluate the effect
of this processing
method/ Cooking time on their
nutritive value and antioxidant properties.
The result of
the study revealed
that longer time of
cooking (higher than
15 min) caused negative
impact by reducing
nutritive value but
positive impact by
reducing anti-nutrients such as
oxalates and phytates.
The registered losses
at 15 min
were as follow:
ash (12.42 – 54.09 %),
proteins (3.47 -
33.23 %), vitamin
C (46.42 –
83.21 %), carotenoids
(73.74 – 100
%) oxalates (19.29 –
59.86 %) and
phytates (28.61 –
78.02 %).The average
reduction of polyphenols
content at 15 min
of cooking was
9.95 – 59.43
%. Contrary to
these reductions, a
slight increase of
fibres content was observed
in the studied
cooked leafy vegetable ?Chochorus olitorius). Furthermore
after 15 min of cooking time
the residual contents
of minerals were:
calcium (119.92 –
512.70 mg/100g), magnesium
(51.94 – 285.07 mg/100g),
potassium (529.92 –
1721.18 mg/100g), iron
(12.37 – 25.63
mg/100g) and zinc (11.53
– 25.03 mg/100g).
All these results
suggest that the recommended time
of domestic cooking must
be less than
15 min for
the studied leafy
(Corchorus olitorius) in
order to contribute
efficiently to the nutritional requirement and to the
food security of Nigerian population.
Background to the Study
Vegetables are the
fresh and edible portions of herbaceous plants, which can be eaten raw or
Cooke's(Fayemi 1999, Dhellot et al., 2006). They contain valuable food
ingredients which can be successful utilized to buildup and repair the body.
They are valuable in maintainiy alkaline reserve of the body. They are valued
mainly for their high carbohydrate, vitamin and mineral contents. Corchorus
olitorius is a popular edible vegetable in Nigeria. It is usually recommended
for pregnant wen and nursing mother because it is believed to be rich in iron
(Oyedele et al., 2006).
both essential and toxic events over a wide range of concentrations
(Ajewole,1999). The concentration of these elements is a function of the
concentrations in the soil in which the vegetable is planted. Leafy vegetables
are regular ingredient in the diet of the average Nigeria with their level of
consumption, they can provide appreciable amounts of nutritive minerals
The importance of the
nutritional status of vegetables by Nigerians has resulted in the increased
demand of knowledge of the nutrient of food. Green leafy vegetables are
important component of the dietary regime of humans because they provide the
necessary vitamins and minerals (Fasuyi, 2006). They however also contain anti
nutrients which reduce the bioavailability of these nutrients (Akindahunsi and
Salawu, 2005, Binita and khetarpaul, 1997). Aletor and Adeogun, (1995) however,
reported that some anti nutrients exhibit protective effects thus making them
serve dual purpose. Oxalate binds to calcium to form calcium oxalate crystals,
these prevent the absorption and utilization of calcium by the body thereby
causing diseases such as rocket and osteomalacia (Ladeji et al.,2004). Phytic
acid combines with some essential elements such as Fe, Can, Zn and P to form
insoluble salts called the phytayes which are not absorbed by the body
therefore making these minerals biounavailable. Saponins are naturally oily
glycosides occurring in wide variety of plants. When eaten, they are non
poisonous to warm blooded animals but are poisonous when injected into the
blood stream (Applebaum et al., 1969).
Tannins are water
soluble soluble phenolic compounds with a molecular weight greater than 500 and
with the ability to precipitate proteins from aqueous solution. They occur
almost in all vascular plants. They combine with digestive enzymes thereby
making them unavailable for digestion (Abara, 2003, Bonita and khetapaul,
1997). Despite the fact that the leafy vegetable Corchorus olitorius are widely
consumed because of its accepted nutritional value, the adequate cooking time
and the effect it has on the anti nutritional factors has not been established.
Hence, there is need to do so.
(Ewedu) are widely consumed because of the accepted nutritional value. Despite
this there is lack of sufficient information on the anti nutritional factors
and adequate cooking time of these vegetable. Hence there is need to determine
the effect of cooking time on anti nutritional factors and establish an
adequate cooking time for it.
Objectives of the Study
The major objective
of the study is to determine the effect of cooking time on anti nutritional
factors and adequate cooking time of Corchorus olitorius (Ewedu).
(1) where is Ewedu
(2) what are the
nutritional benefit of Ewedu?
(3) what are the anti
nutritional factors present in Ewedu?
(4) what quantity of
Corchorus olitorius (Ewedu) will be enough for the research.
Significance of the Study
The study gives a
clear insight into the anti nutritional factors present in Corchorus olitorius
and the effect of cooking time on the anti nutritional factors. The study will
also establish an adequate cooking time for it to prevent overcooking or
undercooking by consumers.
Scope of the study
The research focuses
on the effect of cooking time on anti nutritional factors and adequate cooking
time of Corchorus olitorius (Ewedu).