Structural and physicochemical characteristics of starches from sorghum varieties with varying amylose content

Six sorghum varieties containing different amylose were selected to investigate the structural and physicochemical characteristics of starches and endosperm texture of grains. The results showed that the outer layer endosperm of sorghum grain changed from waxy to corneous, and its starch granules were more compactly packed and exhibited the spindle-shaped holes with the increase of amylose content. Higher amylose starch granules exhibited fewer and smaller micropores on the surface and were more likely to deform and agglomerate into larger amorphous particles after heated. Amylose content of sorghum starches was negatively correlated to granule size, relative crystallinity, and the proportion of the long branch chains (DP = 25-36 and > 36), whereas positively correlated to the proportion of the short branch chains (DP = 6-12 and 13-24). Amylose content had negative correlations with T-o, T-p, Delta H, PV, and SDS (p < .05), positive corrections with FV, SB, and RDS (p < .05), and no correlations with T-c, HPV, BD, and RS. It could be concluded that amylose content affected the endosperm texture of sorghum grain and had strong correlations with structural and physicochemical properties of sorghum starch. These findings may help identify uses for these sorghum varieties in baijiu production.