CHAPTER ONE

INTRODUCTION

Sweet potato (Ipomoea batatas) is an important food crop in the

tropical and sub tropical countries and belongs to the family convolvulaceae.

It is cultivated in more than 100 countries. ( Woolfe 1992). Nigeria is the

third largest producer in the world with china leading followed by Uganda.

Sweet potato ranks seventh among the world food crops third in value of

production and fifth in caloric contribution to human diet (Bouwkamp

1985). Sweet potatoes are rich in dietary fibre minerals vitamins and anti

oxidants such as phenolic acids anthocyanins tocopherol and ß- carotene.

Besides acting as anti oxidants carotenoids and phenolic compounds also

provide sweet potatoes with their distinctive flesh colours ( cream deep

yellow orange and purple). Sweet potato blends with rice cowpea and

plantain in nigerian diets. It is also becoming popular as a substitute to yam

and garri. It can be reconstituted into fofoo or blended with other

carbohydrate flour sources such as wheat ( Triticum aestivum) and cassava

( Manihot esculenta) for baking bread biscuits and other confectioneries

(Woolfe 1992).

The leaves are rich in protein and the orange flesh varieties contain high beta

carotene and are very important in combating vitamin A deficiency

especially in children.

Sorghum (sorghum bicolor (S. bicolor) is a tropical plant belonging to

the family of poaceae is one of the most important crops in Africa Asia and

Latin America. More than 35% of sorghum is grown directly for human

consumption. The rest is used primarily for animal feed alcohol production

and industrial products ( FAO 1995). The current annual production of 60

million tons is increasing due to the introduction of improved varieties and

breeding conditions. Several improved sorghum varieties adapted to semi-

arid tropic environments are released every year by sorghum breeders.

Selection of varieties meeting specific local food and industrial requirements

from this great biodiversity is of high importance for food security. In

developing countries in general and particularly in West Africa demand for

sorghum is increasing. This is due to not only the growing population but

also to the countries policy to enhance its processing and industrial

utilization.

More than 7000 sorghum varieties have been identified therefore there is a

need of their further characterization to the molecular level with respect to

food quality. The acquisition of good quality grain is fundamental to

produce acceptable food products from sorghum. Sorghum while playing a

crucial role in food security in Africa it is also a source of income of

household . In West Africa ungerminated sorghum grains are generally used

for the preparation of "to" porridge and couscous. Malted sorghum is used

in the process of local beer "dolo" (reddish cloudy or opaque) infant

porridge and non fermented beverages. Sorghum grains like all cereals are

comprised primarily of starch.

The aim and objective of this work is to obtain diet low in sugars with

enriched nutrients intended for diabetics.