Starch characteristics of cowpea and mungbean cultivars grown in Korea

Physicochemical properties of starches from 5 different Korean cultivars of cowpea and mungbean were examined. Starch granules had elliptical to spherical granules. Volume median diameter of granules ranged from 17.0 mu m to 48.6 mu m, with a significantly larger median granule diameter in cowpea starches than mungbean starches. Apparent amylose content ranged from 35.7% to 38.5%. Among cowpea starches, Seowon had a higher molecular weight and longer amylopectin average chain length than other cultivars. Between mungbean starches, Sohyun had a lower amylose molecular weight but a longer amylopectin average chain length than Dahyun. The relative crystallinity and gelatinization enthalpy of cowpea starches were greater than those of mungbean starches. Okdang had higher peak and final viscosities than other cowpea starches, whereas two mungbean varieties showed similar values for pasting parameters. Seowon in the cowpea starches and Sohyun in mungbean starches had higher gel hardness than other cultivars.