Composite films based on a novel protein and chitosan: characterization and properties.

Lacquer trees (Toxicodendron vernicifluum (Stokes) Barkl.), a significant economic tree species in China, can be availed in the wax/oil industry as its seeds residues contain 43 wt% of amino acids. Films based on Lacquer tree seeds residues protein (LSP) were prepared with casting method and characterized to evaluate the probability of the new protein resource for industry. Besides, chitosan (CH) can help enhance the LSP film performance as an additive. The films' mechanical properties, antibacterial activity and water vapor permeability were measured by tensile strength and elongation at breaking, inhibition zone test, and bottle weighting method, respectively, while Fourier transform infrared spectrum, X-ray diffraction, and scanning electron microscopy were employed to characterize the structure of films. The differences among films were evaluated by the variance analysis via Duncan's multiple range tests. As a result, CH improved the film-forming, water resistance, and mechanical properties of LSP films. CH fused well with LSP to form an agglomerated structure when the mass fraction of CH was over 50%. In addition, the film containing 75 wt% CH and 25 wt% LSP showed higher water resistance and elongation at breaking than 100% CH film. All of the LSP composition films inhibited the growth of S. aureus. However, the composite films showed lower toughness than the carbohydrate film due to the phase separation of the two polymers. LSP-based films showed high application potential for inner packaging due to their outstanding properties. [ABSTRACT FROM AUTHOR]