World Journal of Engineering Research and Technology

A. S. Ajala*, F. A. Morufu and K. O. Lawal

ABSTRACT

Water yam is a perennial herbaceous vines cultivated for the consumption of their starchy tubers and also serve as a source of income for people in West Africa. The principal problem in water yam is that it underutilized and its price is lower compare to other yam varieties in the market. Thus it is necessary to develop other means of utilizing it to check its low value price so that farmers can earn better money from planting and sale of the yam. In this study, water yam (D. alata) flour was prepared using standard milling process. The flour was evaluated for proximate composition, functional (loose density, packed density and swell capacity) and anti-nutritional (phytate, saponin and tannin) properties. It was mixed with wheat flour at varying proportion (100:0, 90:10, 80:20, 70:30, 50:50) and baked as breads. The composite breads were evaluated for minerals (Ca, P, Zn, Mg and Na) and sensory attributes. The results of the proximate composition of yam flour are as follows: moisture (12.26-14.60) %, protein (3.50-6.73) %, fat (0.45- 0.83) %, ash (1.94-2.59) %, crude fibre (1.57-1.74) % and carbohydrate content (75.85-77.92) %. The results of physico-chemical properties of yam flour are as stated; swelling capacity (13.81-15.51)cm3/g, loose bulk density (0.51-0.56) g/cm3 and packed bulk density (0.65-0.70) g/cm3. The results of anti-nutritional are: phytate (0.01-0.02) mg/kg, saponin (0.14- 0.16)mg/kg and tannin (0.01- 0.04)mg/kg . The results of minerals in the bread are as stated: Ca (380-620) mg/ kg, P (1195-1405) mg/ kg, Zn (7.40- 9.65) mg/ kg, Mg (25.90-35.35) mg/ kg and Na (101.01-333.02)mg/ kg. The sensory results of the bread are: aroma (1.25-2.60), colour (1.30-3.40), taste (1.4-3.50), texture (1.55-3.45), appearance (1.40-3.80) and overall acceptability (1.25-3.50). The varied proportion of water yam flour to wheat flour had a significant effect on colour, aroma, taste, texture of the bread. The result of the research showed that up to 10% inclusion water yam flour could be used in composite breads and still be acceptable sensorially. This indicates that water yam hitherto underutilized could be inculcated into wheat flour to produce composite bread. This will add value to the yam locally and reduce dependence on wheat importation into the country.

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