Comparison of structural and physicochemical properties of starches from five coarse grains

Starch, one of the most important components of coarse grains, has received widespread attention because of its prominent potential health benefits. In the present study, we isolated starches from the grains of sorghum, tartary buckwheat, common buckwheat, mungbean, and pea and studied their structural and physicochemical properties. These five starches all showed the distinctive Maltese cross effect (birefringence) but significantly differed in morphology, size, and complexity of granules. Sorghum starch exhibited the lowest amylose content and highest weight-average molar mass. Mungbean contained more short amylopectin [degree of polymerization (DP) 612 = 23.4%]. Pea starch exhibited the highest amylose content, highest amylopectin average chain length, and lowest weight-average molar mass. The starches of sorghum, tartary buckwheat, and common buckwheat showed A-type crystallinity, whereas those of mungbean and pea showed C-type crystallinity. Our results provide useful information for the application of coarse grain starches in diverse industries.