Chemical, functional and sensory properties of water yam – cassava flour and its paste

Elubo flour is usually produced from traditionally steeped and dried yam (Dioscorea rotundata) slices/tubers while lafun flour is a fermented cassava product. During the off season of yam, the elubo retailers tend to mix water yam elubo (Dioscorea alata) with lafun to obtain a seemingly yam flour. Water yam flour elubo replacement substitute with cassava flour lafun were evaluated in terms of the chemical, functional properties of the flour and sensory attributes of its cooked thick paste amala. The water yam and cassava flours were blended in the ratios of 100:0, 90:10, 80:20, 70:30, 60:40, 50:50 respectively and 100% yam flour elubo as the control. The pH decreased from 3.82 to 3.42 and cyanide content increased from 0.020 to 0.032 mg HCN/100g as the amount of lafun in water yam flour was increased. Bulk density (0.55-0.67g/ml), Water binding capacity (278.51-381.18%) and water absorption index (61.67-84.21%) increased with increase in amount of lafun in water yam flour, thus improving the reconstitution ability. The peak, trough and final viscosities increased; there was no significant difference (p 0.05) in breakdown and setback viscosities respectively while peak time and pasting temperature decreased, as the amount of lafun in water yam flour was increased. The amala paste prepared from sample 70:30 was the most acceptable in terms of colour, taste and aroma.