Preparation of self-reinforced starch films for use as hard capsule material

A strategy for preparation of self-reinforced starch films for use as hard capsule material is introduced. In this study, the hydroxypropylated-crosslinked potato starch (HCPS) was prepared and used to reinforce the hydroxypropylated-hydrolyzed potato starch (HHPS) films. The paste properties of starch samples and the morphology of starch films were investigated by a rapid visco analyzer (RVA) and scanning electron microscope (SEM), respectively. It was found that the matrix/particle interface was greatly improved after the hydroxypropylation of crosslinked starch. The strain and toughness of the starch composite films were increased by about 30% and 50% after addition of 10 wt% HCPS particles, respectively. In addition, the self-reinforced starch film also had good oxygen barrier property, with its oxygen permeating coefficient (OPC) at 5.09 × 10^-12 cm³·cm/cm²·s·cmHg (50% RH). The fragmentation rate of starch capsules has also decreased, indicating it is an alternative material for the preparation of hard capsules.