Fine structure and relationships with functional properties of pigmented sweet potato starches.

Variations in fine structure of pigmented sweet potato starches and their relationships with starch functional properties were explored in this study. The amylose content (18.63-20.45%), XAM1 (308-387) and hAP2 (0.723-0.810) and hAM2 (0.134-0.167) significantly differed (P < 0.05), while other structural parameters had small variations. The average chain length of amylopectin ranged in degree of polymerization (DP) from 23.3 to 24.7. The proportions of fa, fb1, fb2 and fb3 were 21.88-27.18%, 45.45-50.81%, 11.87-13.29% and 14.02-16.96%, respectively, with significant (P < 0.05) differences among these samples. Pearson correlation analysis indicated that fine structures of both amylose and amylopectin had significant impacts on pasting, gelatinization, and textural properties. XAM2, fa, fb1, XAM2 and fa/fb1 were significantly correlated with pasting parameters, while fa and fa/fb1 were negatively correlated with thermal parameters. XAM1 and hAP2 were negatively correlated with texture. These results may provide an overview of structure-function correlations for sweet potato starches.