Effect of Sodium Alginate on the Properties of Composite Protein Films

Effects of sodium alginate on properties of WPI-NaCas composite films optimized by previous uniform design experiments were investigated. Films were prepared with different concentrations (1%, 2%, 3%) and ratios (1:0, 5:1, 3:1, 1:1, 1:3, 1:5, 0:1, ratio of composite protein solution to sodium alginate solution) of sodium alginate additions. Results suggested increases in water solubility of films and middle diameter, volume-length mean diameter and area-length mean diameter of film-forming solutions. Addition of sodium alginate decreased the gas and water vapor barrier properties of composite films, however, their mechanical properties could be improved by proper usage. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope analysis indicated that protein and sodium alginate presented well interaction and compatibility.