Rheological and Functional Properties of Soy-Poundo Yam Flour

Abstract

The nutrition of the people of developing countries is a major public health issue which has challenged breeders to enhance the nutritional quality of preferred and staple crops such as yam. This project therefore aimed at evaluating the effect of soy flour enrichment on the rheological properties of poundo yam flour. The yam flour was substituted with soy flour at varying proportions (100:0; 90:10; 80:20; 70:30) with the aim of producing a more nutritionally balanced product (poundo yam). Reconstituted poundo yam dough was prepared from all the flour samples and was evaluated for consumer acceptability. Data obtained showed that the functional properties i.e. swelling power (2.70-3.34%) and solubility (16.16-20.23%) increased significantly (P≤0.05) with increasing substitution levels of soybean with a corresponding decrease in the bulk density (0.84-0.71) and dispersibility (60.50-52.50) and water absorption capacity (267.76-260.62%) as the substitution levels of soybean increases. The substitution of soy flour into yam flour affected the rheological properties of yam flour; the rate of water absorption of the yam flour decreased as soy flour substitution levels increased. Also, the dough stability time of the enriched flours was higher than that of the yam flour. The 30% enrichment level had the highest dough consistency (283FU). The extensibility of the enriched flour blends increased upon increasing levels of soy flour substitution. The 20% flour blend had the highest resistance to highest resistance to extension. Soybean flour substitution also increased the amino acid profile of the poundo yam. The poundo yam made from this flour blends also varied in texture, aroma, taste and colour. Apart from adding value and varieties to poundo yammeal due to its colour and textural improvement, enriching yam flour with soybean flour at 10% level would also reduce the problem of food security especially among children in the sub Sahara region of Africa where malnutrition due to protein deficiency is prevalent.