Thus, the solubility of the NRS and DMRS films most likely reflected the leaching of plasticizer, starch chains and a hydrophilic modification reagent from the film matrix after 24 h immersion in water. The results demonstrate that FS of DMRS film from HPC2 (2% STMP and 5% STPP) showed higher values than the HPC1 (2% STMP). This was because the amount of phosphate groups in the HPC2 was higher than in the HPC1, which was noted in the higher DS values in the resulting starch (Table 1).