Thesis Abstract

Abstract
The African yam bean (Sphenostylis stenocarpa) is a leguminous crop commonly grown in sub-Saharan Africa for its nutritional and economic benefits. This study aimed to investigate the influence of different processing methods on the protein content and cyanide levels in African yam bean seeds. The processing methods included soaking, boiling, and roasting, which are commonly used by local communities to prepare the seeds for consumption. Results showed that soaking significantly reduced the protein content of African yam bean seeds compared to the raw seeds. Boiling also led to a decrease in protein content, although to a lesser extent than soaking. In contrast, roasting had the least impact on the protein levels of the seeds. These findings suggest that the processing method employed can affect the protein content of African yam bean seeds, with soaking being the most detrimental in terms of protein preservation. Cyanide is a toxic compound found in many plant foods, including legumes like African yam bean. The study found that all three processing methods led to a reduction in cyanide levels in the seeds compared to the raw, unprocessed seeds. Soaking was the most effective in reducing cyanide content, followed by boiling and roasting. This indicates that processing methods can play a crucial role in detoxifying African yam bean seeds and making them safe for consumption. Overall, the results of this study highlight the importance of considering processing methods when evaluating the nutritional and safety aspects of African yam bean seeds. While processing can lead to a reduction in protein content, it can also help in lowering cyanide levels, thus enhancing the overall safety of the seeds for human consumption. Further research is needed to optimize processing methods that can strike a balance between preserving the nutritional quality of African yam bean seeds while ensuring food safety.

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.