Structure-stabilizing effect of glycerol on amylose promotes the formation of V-type starch with controlled digestibility.

This study presents a simple approach to preparing V-type starch with low digestibility by inducing the conformation variation of amylose. Differential scanning calorimetry revealed that when the glycerol concentration was increased, the peak temperature of starch increased from 72.75 to 135.31 °C, indicating a typical concentration dependence. This process was accompanied by the destruction of the crystalline structure and the expansion of starch particles. When the gelatinizing medium was changed from water to glycerol, the short-range ordered structure of V-type starch was improved and the sample's crystallinity was increased by 29.01 %. Molecular dynamics simulations revealed that in the glycerol system, amylose exhibited a more concentrated dihedral angle distribution at approximately φ = 83.64° and ψ = 98.18°, signifying that the amylose had a more stable and uniform V-type helical structure. Compared with the water system, the average H-bonds number and Lennard-Jones potential energy in glycerol system increased from 2.52 to 3.36 and decreased from -322.93 to -761.86 kJ/mol, respectively, indicating that glycerol molecules interacted with amylose and stabilized its conformation through hydrogen bonds and van der Waals forces. Furthermore, the V-type starch with perfect crystals prepared in pure glycerol had a 25.06 % higher resistant starch content than did the sample prepared in pure water.