Development of chitosan/squid skin gelatin hydrolysate films: Structural, physical, antioxidant, and antifungal properties

Chitosan (85% deacetylated, viscosity > 400 MPa, and molecular weight of 570.3 kDa)/squid gelatin hydrolysates (SGH) were prepared by incorporating SGHs (10%, 20%, and 40%) into chitosan films. SGH were obtained from squid skin gelatin by hydrolysis with Alcalase. The effects of adding SGH on the physical, chemical structure, mechanical, degradability, antioxidant, and antifungal properties of the chitosan films were evaluated. Films containing SGH were opaquer and more colored than the reference. Scanning electron microscope imaging showed that the surface sections of the CH/SGH films were smooth and homogeneous, though a small amount of insoluble microparticles was observed. Atomic force microscopy indicated that the surface roughness of the chitosan films increased with the addition of SGH. Fourier-transform infrared spectroscopy and nuclear magnetic resonance spectroscopy suggested an excellent compatibility of the components due to hydrogen bonding. The flexibility and in vitro degradability of the films increased as the SGH content increased. The 2,2^′-azino-bis(3-ethylbenzothiazoline-6-sulfonate acid and 1,1-diphenyl-2-picrylhydrazyl scav-enging rate of films increased with the addition of SGH. Moreover, films containing 20% SGH improved the fungistatic activity against Aspergillus parasiticus of chitosan films. The chitosan/SGH composite films have the potential for use in food packaging.