Improved mechanical properties and thermal-stability of collagen fiber based film by crosslinking with casein, keratin or SPI: Effect of crosslinking process and concentrations of proteins

This study utilized three different thermo-stable proteins of casein, keratin and soy protein isolate (SPI) to improve the thermal stabilities and mechanical properties of collagen fiber films using transglutaminase (TGase) crosslinking. The crosslinking greatly enhanced the thermal- stability of collagen fiber films, especially that of the collagen fiber crosslinking with 50% casein composite films, judged from thermogravimetric analysis (TGA). Furthermore, the TGase treatment improved the mechanical properties of the collagen fiber films interms of tensile strength (TS) and elongation at break (EAB). Importantly, a prominent improvement in EAB at wet and heated state was noted when collagen fiber crosslinked with 50% keratin or 50% casein, respectively. Moreover, different addition patterns of proteins in the collagen fiber films offered altered morphology as observed by scanning electron microscopy (SEM). Meanwhile, the conformational changes of the films revealed by fourier transform infrared spectroscopy (FTIR) confirmed a greater stabilization of film in the group of collagen fiber crosslinking with other proteins. In conclusion, the crosslinking action induced by TGase between collagen fiber and higher thermo-stable proteins promoted heat-resistance and mechanical properties of collagen fiber based film.