Formation of the rosette-like starch with enhanced V-type crystallization via modified solvent-shifting method

This research investigated the effect modified solvent-shifting method on the formation, ordered structure, and morphology of V-type starch. Ionic liquid (IL) dissolution and hot ethanol aqueous incubation in gradient concentrations from 30 % to 80 % (v/v) were applied to optimize the relative crystallinity of V-type starch. The results showed that this new method worked in producing V-type conformation, and higher ethanol concentration tended to yield V-type starch with higher crystallinity and more disk-like shape structure within the ethanol range of 30-50 % (v/v). Notably, the crystalline order of V-type starch reached the maximum with a specific rosette-like morphology under the condition of an ethanol concentration of 50 % (v/v). While the grown crystals organized into small-size flower-like assemblies and this morphology even disappeared accompanied by the V-type crystallization weakening when starch chains co-crystallized with the ethanol concentrations of 60 %-80 % (v/v). The molecular structure analysis indicated no significant correlation between the relative crystallinity of V-type starch and its fine structure. IL served to promote the formation of V-type starch, while it didn't participate in the formation process and could be removed during the washing process. The findings can provide new insights into developing a bottom-up pathway for regulating crystallization and morphology of V-type starch.