Physicochemical Properties of Processed Aerial Yam (Dioscorea bulbifera) and Sensory Properties of Paste (Amala) Prepared with Cassava Flour

Aerial yam is a member of the Dioscoreaceae family which consist several varieties found in South Asia and Africa. The tubers are under-utilized and not commercially grown; but are cultivated and consumed among rural dwellers in parts of Western Nigeria. The tubers were washed, sorted, peeled, sliced and blanched in hot water at 80ºC for 10min. The blanched yam slices were divided into four portions. Two portions were fermented for 48hr and sun (BFSUD) and solar (BFSOD) dried. The other two blanched portions were also sun (BSUD) and solar (BSOD) dried respectively. The dried slices were milled, sieved and used for proximate, functional and phytochemical analysis. Proximate composition of aerial yam flour was: moisture content (7.66-10.60%), total ash (0.05-1.76%), crude protein (4.42-5.07%), crude fibre (0.56-0.69%), crude fat (3.42-3.82%), and carbohydrate (79.28-82.37%). The phytochemical constituent included alkaloid, steroids, saponin and flavonoid. The bulk density, water absorption capacity and dispersibility were within the range of 0.52-0.54g/ml, 56.50-66.00g/g and 4.47-5.75% respectively. The sample, BFSUD had the highest crude protein, dispersibility and water absorption capacity was selected and mixed with cassava flour for amala on which sensory evaluation was conducted. Five aerial yam flour (AY) treatments were formulated and coded as follow: AY100, AY80CS20, AY60CS40, AY40CS60, and AY20CS80. Cassava flour (CS100) was used as control treatment. The overall acceptability of flour paste (amala) ranged from 5.45 (Sample AY80CS20) to 7.25 (sample AY100). The study revealed treatment AY60CS40 and AY80CS20 possessed the overall acceptability, mean score above 7.0 (like slightly). Therefore 60-80% incorporation of aerial yam flour with cassava is recommended based on desirable sensory characteristics. Aerial yam flour can be used for food preparation and commercial purpose which may in turn increase the utilization.