Production of Couscous and French Fries from Dioscorea Alata (Water Yam)

Water yam (Dioscorea alata) has been a lesser choice compared to white and yellow yams. Processing of the tubers into a more stable product will increase shelf life and availability, and enhance its usage. Minimal processing such as peeling, size reduction, and steam blanching of the tubers coupled with refrigeration, increases the shelf life of the tubers and makes them available for fried chip production. Grating and drying of steam blanched samples yielded couscous. Fries of two different sizes, large (5 cm long × 1.5 cm thick) and small (5 cm long × 0.5 cm thick) from each variety were steam-blanched under different time regimes (5, 10, and 15 minutes). The pasting temperature, peak viscosity, hot viscosity, cold viscosity, and set back viscosity were significantly different (P < 0.05). The peak viscosity was negatively correlated to the pasting temperature (r = –0.65). The serving temperature is very important to the eating qualities of couscous prepared from Dioscorea alata. The small size chips were the preferred choice of the consumers and there were no significant difference in the sensory attributes among the different blanching times. The varieties suitable for couscous processing were TDa 297, TDa 98/01176, TDa 291, TDa 99/00528, TDa 98/01168, and matches. TDa 98/01176, TDa 98/001168, TDa 291, and matches were also the most preferred varieties for French fries.