INFLUENCE OF PROCESSING METHODS ON THE PROTEIN AND CYANIDE CONTENT OF AFRICAN YAM BEAN SPHENOSTYLIS STENOCARPA

Project Abstract

African yam bean (Sphenostylis stenocarpa) is a leguminous crop widely consumed in Africa due to its high nutritional value. However, the presence of antinutritional factors such as cyanogenic glycosides poses a health risk if not effectively reduced during processing. This study aimed to investigate the influence of various processing methods on the protein content and cyanide levels of African yam bean. Three processing methods, namely soaking, boiling, and fermentation, were employed to process the African yam bean samples. Results indicated that soaking significantly reduced the protein content of African yam bean compared to the raw samples. Boiling led to a slight decrease in protein content, while fermentation showed a minimal effect on protein levels. In terms of cyanide content, soaking significantly reduced cyanide levels in the African yam bean samples. Boiling also led to a reduction in cyanide content, with longer boiling times resulting in lower cyanide levels. Fermentation showed the most significant reduction in cyanide content compared to the other methods. Overall, the results suggest that processing methods have a significant impact on both the protein content and cyanide levels of African yam bean. Soaking and boiling were effective in reducing cyanide content, with fermentation showing the most promising results. However, it is essential to balance the reduction of cyanide levels with the preservation of protein content during processing to maintain the nutritional quality of African yam bean. Further research is needed to optimize processing methods for African yam bean to ensure the highest possible protein content while minimizing cyanide levels for safe consumption.

Project 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.