Raw African Yam bean (Sphenostylis stenocarpa) was subjected to various processing methods Viz: steeping in water for 6 hr and then boiling for 10, 20, 30, minutes respectively (samples B); steeping in water for 12 hours and then boiling for 10, 20, 30, minutes respectively (sample C) and finally sample A was raw yam bean which served as control. The entire sample was dry – milled into fine flours. The glycosidic cyanide, crude protein, ash, moisture, some functional properties and bulk density of the flours were analyzed from the results, protein and cyanide content of sample A (raw sample) are 25.20% and 72.23ml. results showed that the toasting, process gave the highest protein (24.12) with no trace of cyanide and it negatively affected the protein content of the samples reducing it from 25.20 to 17.57, 17.51(%) respectively. 12 hours soaking and few minutes boiling process negatively affected the protein content of the samples reducing it from 25.20% to 13.12, 12.78, 12.09 (%) respectively but have the strongest impact in covering the cyanide level from 72.23ml to zero respectively. Moisture content ranges from 400% - 14%, Ash ranges from 2.50% to 5.00%, water absorption ranges from 105g/ml to 290g/ml, oil absorption ranges form 0.98 – 1.95g/m. The bulk density showed 0.74g/ml – 0.88g/ml.
2.1 Legumes
2.7.0 Functionality of Legume Protein/Flour
3.0 Materials And Source
Results / Discussion
Conclusion and recommendation
References
African yam bean (Sphenostylis stenocarpa) belongs to the genera papilliona sec which is in the class known as Leguminousae (Okigbo, 1973). It is one of the neglected indigenous grain legumes in Nigeria. It is produced mostly in the eastern part of the country where it is consumed in different forms such as snacks, delicacy, man meal etc. It can be used for the fortification of other foods (Eke, 1997)
In Nigeria, it has as many names as there are communities cultivating it. Some of the names are Okpdudu, Azam, Uzuaku, Ijiriji, Azara, Ahaja, Nzamiri, Odudu, Girigiri (Hausa), sese (Yoruba) and Nsana (Ibibio) (Ogbo, 2002).
The high protein content of African yam bean makes it an important source of protein in the diets of population groups of many tropical countries (Kon, 1979, Ekpen young and Borchers, 1980). In addition, the high protein bean flour fractions could be substituted for wheat flour to produce acceptable qualities of cookies breads and leavened doughs (Uebersax and Zabik, 1986; Nzereogu, 1993).
It may also be consumed as porridge after cooking. The mature dry seeds can be used to prepare “moi - moi” and “akara” (Ezueh, 1973; Akoma, 1996). The African yam bean apart from being rich in protein also contains carbohydrate, fat and minerals (NAS, 1979).
A major constraint in the utilization of African yam bean is the different dehulling method. Traditionally, the dehulling method involves manual removal of the hulls from the individual soaked seeds. This method is quite laborous (labour intensive), time – consuming and does not favour effective utilization of the bean. It is widely believed that under cooked African yam bean seeds cause diarrhoea and over cooked seeds cause constipation (Asusu and Undie, 1986).
Previous works showed that steeping will among other things improve the dehulling characteristic of the African yam bean while maintaining the nutritional quality viz: invitro protein digestibility and also improving the functional properties when processed into flour (Abbey and Berezi, 1988). It is evident that better processing methods will not only enhance the acceptability and utilization of this legume but will also improve the nutritional status of the consuming populace (Uebersax et al, 1989).
The overall objective of this study is to investigate the various processing methods and their effects on the protein and cyanide content of African yam bean in conclusion, before the commencement of any research or project, there is meant to be aim/aims of such research.
As such, the aims of this study include:-
2.1 LEGUMES
Food legumes are classified into two viz: the pulse and oil seeds. The pulses are those species of legumes harvested traditionally for their mature seeds and are major sources of dietary proteins and calories in food and feed products throughout the world (Ihekoronye and Ngoddy, 1985). Examples of pulse legumes include pigeon pea, cowpea, and chick pea while the oil seeds consist of those legumes uded primarily for their oil content which may be extracted by pressing or by solvent extraction. These include groundnuts and soybeans (Ihekoronye and Ngoddy, 1985).
The pulse legumes are also rich in digestible carbohydrate mainly starch and concentrations of 50% or more are common. Legume seeds rich in carbohydrate are noted t o contain relatively small amounts of lipids mainly as phopholipids (Duke et al; 1979). When consumed, they lower serum cholesterol level and this probably may be related to the high soluble storage polysaccharide contained in the seeds (Anderson et at; 1984).
Some legumes apart from being rich in proteins and carbohydrates, are also good sources of lipids, dietary fibbers, vitamins and mineral (Duke et at; 1979). The fat content of legumes is less than 3% with exception of some like groundnuts and soybeans and naturally contains an appreciable level of water (Ihekorony and Ngoddy, 1985). Legumes are also known to contain ant-nutritional factors such as lectin, saponine, phytin and trypsin inhibitors (Eneobony et al; 1996).
The legume seeds are second only to the cereals as sources of human food and provide the much needed protein to our predominantly vegetarian population (Giami et al; `992). Legumes contain 17 to 30% protein in a dry basis which is nearly twice or thrice the value found in cereals and 20 times that of cassava with soybean having as high as 42% protein (Giami et al; 1992). Legumes are good sources of lysine, tryptophan and threonine but are low in the sulphur containing amino – acids - metthionine, cystine and cystein (Evans and boulter, 1974).
In addition to protein content, legumes contain upto 60% carbohydrate mainly in the form of starch granules – amylase and amylopectin. While sucrose is the major sugar in legumes (Ihekoronye and Ngoddy, 1985). The fat content of most legumes range from 1 – 2% with oleic and linoleic acids being the main unsaturated fats and oils while palmitic acids are saturated (Deboland et al; 1975).
Deboland et al; (1975) also reported that legumes contain reasonable amount of macin and riboflavin which are ten times and five times respectively, more than those of most cereals and with some amounts of carotene. The sprouted seeds were found to be good source of ascorbic acid.
The proximate composition of some common legumes are shown in
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