Physicochemical properties of five cocoyam (Colocasia esculenta and Xanthosoma sagittifolium) starches

Physicochemical properties of starches of five cocoyam cultivars were evaluated. CIE L*, a*, b* colour parameters of corm and starches were measured. Amylose, pasting and functional properties of the starches were investigated using colourimetric, Rapid Visco-Analyser and standard methods respectively. Cocoyam starches were white in colour as shown by L* (84.83-88.65), a* (+0.01-+1.19), and b* (+15.33-+16.54) values. Starch granule sizes varied significantly in length (6.47-13.63 mm) and width (5.36-8.45 mu m), while amylose content ranged from 11.55% (NCe002) to 33.77% (NXs001). Peak (49.09-141.96 RVU), breakdown (49.09-141.96 RVU), final (189.79-327.42 RVU) viscosities, pasting temperature (84.53-88.75 degrees C) and time (4.55-4.97 min) varied significantly (p<0.05) among cultivars. Also, water absorption capacity (21-36%), pH (4.8-5.3), gelling point (60.5-69.5 degrees C), foam capacity (4.46-18.28%), bulk density (0.14-1.15 g/mL) and swelling power (2.31-10.09) varied significantly (p<0.05) among the cultivars. Average yield of the starches varied significantly from 10.03 (NCe001) to 18.61% (NXs001). (C) 2012 Elsevier Ltd. All rights reserved.