Relationship between starch fine molecular structures and cooked wheat starch digestibility

The molecular structures of starch in cooked wheat were measured and related to its in vitro digestibility. The structures were characterized by size-exclusion chromatography (SEC) and fluorophore-assisted carbohydrate electrophoresis (FACE) to measure the chain-length distribution (CLD) of amylose and amylopectin chains and the whole-molecule weight distribution. The CLDs were fitted to two biosynthetic models, one for amylopectin and another for amylose, which reduced the data to a small number of biologically significant parameters expressing enzyme activities. The digestibility of starch was greatly influenced by medium amylose chains, and the percentage of total starch digested at a long time (C∞) was negatively correlated with the amount of medium amylose chains (hAm,ii) and positively correlated with the length of medium amylose chains (βAm,ii). These results suggested that the medium amylose chains reduced the total digestible starch fraction. This study may help in making informed decisions about wheat starches to aid the formulation of wheat-based diets for conditions such as diabetes.