Physico-mechanical properties of gelatin films modified with Lysine, Arginine and Histidine

The aim of this work was to evaluate the plasticizing effect of Lysine (Lys), Arginine (Arg) and Histidine (His) on gelatin films. Gelatin films incorporated with Lys, Arg and His at different levels (0, 0.5 and 1.0%) were prepared. The films without amino acids were prepared as controls. The addition of Lys increased the elongation at break (EAB) but decreased the tensile strength (TS) compared to the control, especially at 1.0% incorporated level. Arg had cross-linking effect on gelatin films through hydrogen bonds demonstrated by FTIR Analysis, which increased TS of the films. His films showed worse EAB, transmission and transparence compared to the control. Furthermore, the addition of Lys and His reduced L* value and a* value with the coincidentally increased b* and ΔE* values compared with the control. Thermal stability (DSC) and UV light barrier of gelatin films were improved by the addition of three kinds of amino acids. Thus, Lys and Arg had potential to improve the properties of gelatin films as natural plasticizer and cross-linker, respectively.