Effects of processing methods on the physicochemical properties of sweet potato and sorghum

Thesis Overview

<p> INTRODUCTION<br>Sweet potato (Ipomoea batatas) is an important food crop in the<br>tropical and sub tropical countries and belongs to the family convolvulaceae.<br>It is cultivated in more than 100 countries. ( Woolfe, 1992). Nigeria is the<br>third largest producer in the world with china leading, followed by Uganda.<br>Sweet potato ranks seventh among the world food crops, third in value of<br>production and fifth in caloric contribution to human diet (Bouwkamp,<br>1985). Sweet potatoes are rich in dietary fibre, minerals, vitamins and anti<br>oxidants such as phenolic acids, anthocyanins, tocopherol and ß- carotene.<br>Besides acting as anti oxidants, carotenoids and phenolic compounds also<br>provide sweet potatoes with their distinctive flesh colours ( cream, deep<br>yellow, orange and purple). Sweet potato blends with rice, cowpea and<br>plantain in nigerian diets. It is also becoming popular as a substitute to yam<br>and garri. It can be reconstituted into fofoo or blended with other<br>carbohydrate flour sources such as wheat ( Triticum aestivum) and cassava<br>( Manihot esculenta) for baking bread, biscuits and other confectioneries<br>(Woolfe, 1992).<br>The leaves are rich in protein and the orange flesh varieties contain high beta<br>carotene and are very important in combating vitamin A deficiency<br>especially in children.<br>Sorghum (sorghum bicolor (S. bicolor) is a tropical plant belonging to<br>the family of poaceae, is one of the most important crops in Africa, Asia and<br>Latin America. More than 35% of sorghum is grown directly for human<br>consumption. The rest is used primarily for animal feed, alcohol production<br>and industrial products ( FAO, 1995). The current annual production of 60<br>million tons is increasing due to the introduction of improved varieties and<br>breeding conditions. Several improved sorghum varieties adapted to semiarid<br>tropic environments are released every year by sorghum breeders.<br>Selection of varieties meeting specific local food and industrial requirements<br>from this great biodiversity is of high importance for food security. In<br>developing countries in general and particularly in West Africa demand for<br>sorghum is increasing. This is due to not only the growing population but<br>also to the countries policy to enhance its processing and industrial<br>utilization.<br>More than 7000 sorghum varieties have been identified, therefore there is a<br>need of their further characterization to the molecular level with respect to<br>food quality. The acquisition of good quality grain is fundamental to<br>produce acceptable food products from sorghum. Sorghum while playing a<br>crucial role in food security in Africa, it is also a source of income of<br>household . In West Africa, ungerminated sorghum grains are generally used<br>for the preparation of “to”, porridge and couscous. Malted sorghum is used<br>in the process of local beer “dolo” (reddish, cloudy or opaque), infant<br>porridge and non fermented beverages. Sorghum grains like all cereals are<br>comprised primarily of starch.<br>The aim and objective of this work is to obtain diet low in sugars, with<br>enriched nutrients intended for diabetics. <br></p>