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%), X_AM1 (308-387) and h_AP2 (0.723-0.810) and h_AM2 (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. X_AM2, fa, fb₁, X_AM2 and fa/fb₁ were significantly correlated with pasting parameters, while fa and fa/fb₁ were negatively correlated with thermal parameters. X_AM1 and h_AP2 were negatively correlated with texture. These results may provide an overview of structure-function correlations for sweet potato starches.