Thesis Abstract

Abstract
Sphenostylis stenocarpa, commonly known as African yam bean, is a leguminous plant that is a good source of protein and other essential nutrients. However, the presence of cyanogenic glycosides in the plant poses a health risk if not properly processed before consumption. This study aimed to investigate the influence of different processing methods, including soaking, boiling, and fermentation, on the protein content and cyanide levels in African yam bean. The results showed that soaking significantly reduced the cyanide content in African yam bean by 35-45%, depending on the duration of soaking. Boiling also led to a reduction in cyanide levels, with longer boiling times resulting in lower cyanide content. Fermentation was found to be the most effective method in reducing cyanide levels, with a reduction of up to 60% observed after 72 hours of fermentation. In terms of protein content, soaking and boiling were found to have minimal effects, with no significant difference in protein content observed compared to the raw African yam bean. However, fermentation led to a slight decrease in protein content, which could be attributed to microbial activity during the fermentation process. Overall, the findings of this study suggest that proper processing methods can significantly reduce the cyanide content in African yam bean while preserving its protein content. Soaking, boiling, and fermentation were all effective in reducing cyanide levels, with fermentation being the most efficient method. These results have important implications for the utilization of African yam bean as a source of protein and other nutrients in food production. Further research is needed to explore the sensory characteristics and nutritional quality of African yam bean after processing to determine the best method that not only reduces cyanide content but also preserves its nutritional value. Additionally, studies on the bioavailability of protein and other nutrients in processed African yam bean could provide valuable information for incorporating this underutilized legume into diets to address malnutrition and food security issues in Africa.

Thesis Overview

INTRODUCTION
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:-
1. To determine the hydrogen cyanide content of the flour.
2. To analyse for the crude protein content of the flour.
3. To determine some of the functional properties of the flour.
4. Determination of the chemical composition of the flour.
5. To determine the bulk density of the flour.