Film and pharmaceutical hard capsule formation properties of mungbean, waterchestnut, and sweet potato starches

Biodegradable films were developed using mungbean, waterchestnut and sweet potato starches as base raw materials. The physical and mechanical properties of the films were compared with gelatin and HPMC films. The same starches were used to develop hard capsules for utilization in the pharmaceutical industry as a substitute for gelatin or animal based products. Starches with high amylose content had excellent film and hard capsule forming abilities and properties compared to the starches with low amylase content. The starch films also had excellent oxygen barrier properties (0.048 ± 0.008 to 0.070 ± 0.009 fl m/m2 s Pa), but water barrier properties (1.1 ± 0.5 to 1.8 ± 0.4 ng m/m2 s Pa) were higher than LDPE (0.00064 ng m/m2 s Pa) synthetic polymer films. The tensile strength values of starch films (12.1 ± 0.7 to 19.0 ± 2.2 MPa) were not significantly different from gelatin (19.5 ± 1.6 MPa) and HPMC (19.9 ± 1.2 MPa) films. In the case of elongation properties, starch films had lower values (42.2 ± 7.7 to 79.4 ± 9.2%) than gelatin film (122.0 ± 14.6%), but higher than HPMC film (13.8 ± 4.2%). Molecular (SEC-MALLS) and physical (viscosity) characterization of vegetable starches, indicated that the starches with high amylose content produced better biopolymer films and capsules compared to the starches with low amylose and high amylopectin content. Biodegradable films and hard capsules for pharmaceutical applications could be developed from vegetable starches with similar physical and mechanical properties as synthetic and gelatin products.