Physicochemical Properties of Starches of Sweet Potato (Ipomea batata) and Red Cocoyam (Colocasia esculenta) Cormels

Starches of sweet potato (Ipomea batata) and red cocoyam (Colocasia esculenta) cormels were extracted by milling and their proximate compositions, physicochemical properties and pasting properties were analyzed. The starch of sweet potato was observed to possess higher percentage values of crude protein, crude fibre and carbohydrates by difference than that of red cocoyam cormels whereas an opposite trend was observed in terms of their percentage ash content and moisture content. Their fat contents were significantly similar (p < 0.05). The results of the physicochemical properties, including bulk density, water absorption capacity, amylose and amylopectin contents, swelling power and solubility of the starch samples were significantly different (p < 0.05). These properties were found to be influenced by their varying contents of amylose and amylopectin. The results of pasting properties revealed that the paste of sweet potato exhibited higher value of viscosity (405.92 RVU) at lower pasting time (4.37 minutes) than the starch of red cocoyam with paste viscosity of (244.33 RVU) obtained at 4.99 minutes.