Fabrication and characterization of fish gelatin/soluble soybean polysaccharide edible blend films through complex coacervation

Complex coacervation of polysaccharides and proteins is a liquid-liquid phase separation that can occur when they are oppositely charged in aqueous solution. In the present work, soluble soybean polysaccharide (SSPS) and fish gelatin (FG) edible blend films were prepared through pH-induced complex coacervation. The optimal SSPS-to-FG mass ratio (1:3) and pH (5.0) conditions for complex coacervation was determined by measuring the maximum turbidity of SSPS/FG mixtures. The effect of SSPS-FG coacervates on microstructure and properties of SSPS/FG blend films were investigated. Results indicated that the film surface roughness and water contact angle were increased due to the presence of coacervates, while the water vapor permeability and Young's modulus were decreased. The SSPS/FG films containing coacervates had similar optical properties, tensile strength, heat seal ability and water sensitivity but improved thermal stability than the coacervate-free SSPS/FG films. When curcumin was incorporated into SSPS/FG films as an active ingredient, the complex coacervates effectively delayed the release of curcumin from the blend films into lipophilic food simulants. Thus, SSPS/FG blend films fabricated by complex coacervation could serve as potential substrates for developing active food packaging materials with satisfactory properties.