1.1 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).
Vegetables contain 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 (Ajewole,1999).
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.
1.2 Problem Statement
Corchorus olitorius (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.
1.3 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).
1.4 Research Question
(1) where is Ewedu common?
(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.
1.5 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.
1.6 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).
References
Ajewole k. (1999). Analysis of the nutritive elements in some Nigerian leafy vegetables. Processing 23rd Annual NIFST conference. 25-27 October Abuja.
Akindahunsi AA., Salawu S.O. (2005). Photochemical screening and nutrients anti nutrient composition of selected tropical green vegetables .
Aletor V. A., Adeogun O.A. (1995). Nutrients and anti nutrients components of some tropical leafy vegetables. Food chem. 54(4): 375-379.
Applebaum S.W., Mario S., Birky (1969). Saponins are possible factors of resistance of legume seeds to the attack of insects J. Agric. Food chem. 17, 618-620.
Bonita R Khetapaul N. (1997). Probiotic fermentation: Effect on anti nutrients and digestibility of starch and protein of indigenous developed food mixture. J. Nutrient. Health 139-147.
Fasuyi, A.O. (2006). Nutritional potentials of some tropical vegetable meals. Chemical characterization and functional properties. Africa. J. Biotechnology 5(1): 49-53
Oyedele Dj, Asonugho C, Awotoye OO (2006). Heavy metals in soil and accumulated by Edible vegetable after phosphate
