Comparative Characterization of Bovine and Fish Gelatin Films Fabricated by Compression Molding and Solution Casting Methods

Properties and characteristics of films from bovine and fish gelatins prepared by compression molding and solution casting methods were comparatively investigated. Both gelatin films made from compression molding had lower strength, stiffness and tensile toughness, but higher extensibility, water-vapor barrier property and yellowness than those made from casting method (p < 0.05). Moreover, the compression-molded gelatin films exhibited lower thermal stability as indicated by lower glass-transition temperature (T-g) and thermal decomposition temperature (T-d), irrespective of gelatin types. This was mainly attributable to the higher thermal degradation of gelatin taking place during compression-molded film-formation at high processing temperature, as assured by Fourier transform-infrared (FTIR) spectroscopic and free-amino group content analyses. Greater degradation mainly contributing to lower inter-molecular interaction, and molecular order and organization, led to lower overall properties of compression-molded films as compared to cast films. In general, with the same fabrication method and condition used, bovine gelatin films exhibited higher mechanical resistance but lower water-vapor barrier properties and more yellowish than fish gelatin films.