BACKGROUND: The aim of this study was to determine the physicochemical properties of starches isolated from Malawian cocoyams and compare them with those of cassava and corn starches. RESULTS: The purity of the isolated starches varied from 851 to 947 g kg(-1) and pH from 4.93 to 6.95. Moisture, ash, protein, fat and amylose contents ranged from 104 to 132, 0.3 to 1.5, 3.5 to 8.4, 0.9 to 1.6, and 111 to 237 g kg(-1), respectively. Cocoyam starches gave higher potassium and phosphorus but lower calcium levels than the other starches. The shape of starch granules varied from spherical to polygonal with cocoyam starches displaying smaller-sized granules than cassava and corn starches. Cocoyam starches gave a higher wavelength of maximum iodine absorption and blue value but lower reducing capacity values than cassava and corn starches. The extent of acid hydrolysis of the starches also differed. Cocoyam starches exhibited amylopectin molecules of higher molecular weights but amylose molecules of lower molecular weights than cassava and corn starches. Cocoyam starches exhibited lower water absorption capacity and swelling power, paste clarity and viscosity but higher solubility, gelatinisation temperatures and retrogradation tendencies than cassava and corn starches. CONCLUSIONS: The physicochemical properties of native Malawian cocoyam starches vary among the different accessions and differ from those of cassava and corn starches. Copyright (c) 2010 Society of Chemical Industry.
BACKGROUND: The aim of this study was to determine the physicochemical properties of starches isolated from Malawian cocoyams and compare them with those of cassava and cornstarches. RESULTS: The purity of the isolated starches varied from 851 to 947 g kg(-1) and pH from 4.93 to 6.95. Moisture, ash, protein, fat and amylose contents ranged from 104 to 132, 0.3 to 1.5, 3.5 to 8.4, 0.9 to 1.6, and 111 to 237 g kg(-1), respectively. Cocoyamstarches gave higher potassium and phosphorus but lower calcium levels than the other starches. The shape of starch granules varied from spherical to polygonal with cocoyamstarches displaying smaller-sized granules than cassava and cornstarches. Cocoyamstarches gave a higher wavelength of maximum iodine absorption and blue value but lower reducing capacity values than cassava and cornstarches. The extent of acid hydrolysis of the starches also differed. Cocoyamstarches exhibited amylopectin molecules of higher molecular weights but amylose molecules of lower molecular weights than cassava and cornstarches. Cocoyamstarches exhibited lower water absorption capacity and swelling power, paste clarity and viscosity but higher solubility, gelatinisation temperatures and retrogradation tendencies than cassava and cornstarches. CONCLUSIONS: The physicochemical properties of native Malawian cocoyamstarches vary among the different accessions and differ from those of cassava and cornstarches. Copyright (c) 2010 Society of Chemical Industry.