Improving mechanical and barrier properties of cold-water fish gelatin films through sodium alginate and gellan reinforcement for food packaging applications

Cold-water fish gelatin (FG, 5% w/v) was combined with sodium alginate (SA) and gellan (GL) at concentrations of 0.01, 0.05, and 0.1% (v/v) to prepare composite FG films using casting method. The mechanical and barrier (water vapor transmission rate) properties of resulting films were characterized while the film-forming solutions were analyzed using a rheometer and Fourier transform infrared spectroscopy (FTIR). The addition of GL and SA, regardless of concentration, improved barrier properties. GL increased the tensile strength (TS) without affecting the elongation at break (EB), whereas a high concentration of SA (0.1% v/v) led to an improvement in the EB. The viscoelastic behavior of FG film-forming solutions improved with the addition of GL at 0.05 and 0.1% (v/v), whereas SA showed only negligible effects. The FTIR analysis showed a shift in amide I peak to a higher wavenumber in the presence of GL (0.05 and 0.1% v/v), indicating changes in the secondary structures of FG mixtures and their effects on film properties.