Imidazole-based deep eutectic solvents for starch dissolution and plasticization

• We prepared imidazole-based deep eutectic solvents with dissolving activity for starch.
• Investigated DESs are suitable for dissolving high amylose starch.
• Influence of water content in starch and DES on starch modification was analyzed.
• Our thermoplastic starch films do not exhibit retrogradation after 1 month storage.

Potato starch and high-amylose starch were treated with imidazole-based deep eutectic solvents (DESs) as dissolution and plasticization media. Beside imidazole (IM) for two-component DESs preparation choline chloride (CC), glycerol (G) or carboxylic acids (citric or malic) were used. An influence of water content in starch (as well as an extra water in the starch/DES system) on polymer dissolution and plasticization processes was investigated. Dissolution and gelatinization of starch in DESs were followed via DSC and laser scanning microscopy. A rheometric characteristics revealed an influence of starch/DES system storage time on the plasticization process. The tendency to recrystallization of compression-molded-starch films was evaluated using XRD technique. High dissolution and plasticization effectiveness of CC/IM and G/IM and a low tendency to film retrogradation of thermoplasticized starch were noted.