ABSTRACT
This study evaluated “the effects of processing methods on the physicochemical
properties of sweet potato and sorghum flour”. Sweet potato
(Ipomoea batatas) is an important food crop in the tropical and sub-tropical
countries and belongs to the family convolvulaceae. Sweet potatoes are rich
in dietary fiber, minerals, vitamins, and anti oxidants such as phenolic acids,
anthocyannins, tocopherol and β-carotene. The proximate composition of
sweet potato was determined and these include moisture, lipids, ash, protein,
carbohydrates and fiber. In carrying out the analysis practically, methods
used vary according to the food material. The anti oxidants were also
determined alongside with phenol oxidase, pasting properties, minerals and
sugar contents. Sorghum is a tropical plant belonging to the family of
poaceae. More than 35% of sorghum is grown for human consumption. The
analyses carried out in sweet potatoes are same with sorghum with the
exclusion of phenol oxidase.
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 semiarid
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.