Comparison of maize and wheat starch chain reactivity in relation to uniform versus surface oriented starch granule derivatization patterns

Abstract

This study investigated whether different granular reaction patterns of starch derivatives alters the extents of reaction of different starch chain types. Maize and wheat starch granules were derivatized with the fluorescent probe 5-(4,6-dichlorotriazinyl)amino-fluorescein under different reaction conditions to obtain starches derivatized to the same level but either characterized with a surface-oriented or a rather uniform granular reaction pattern. Given the same overall extent of reaction, amylose and amylopectin chains reacted to a greater extent for the starch with a uniform granular reaction pattern, while intermediate chains [100 ≤ degree of polymerization (DPw) < 372] reacted to a greater extent for the starch with a surface-oriented granular reaction pattern suggesting that amylose and amylopectin chains are distributed more homogeneously throughout the granule than the intermediate chains. For both reaction patterns, it was shown that the relative reactivities of intermediate chains were 5.0–9.4 fold higher than the overall reactivity calculated across all starch chains. This study thus teaches that starch chain reactions depends on the granular reaction pattern.