The Study On The Properties Of The Sodium Alginate-based Edible Packaging Film

In this paper, sodium alginate and gum Arabic were made into edible packaging films. The properties of the films were investigated.First, in order to investigate the rheological properties of the film-forming solutions made from sodium alginate and gum Arabic, a Discovery HR-2 rheometer was used to determine rheological properties of the film-forming solutions as affected by different content of sodium alginate, gum Arabic, plasticizer and temperature. The results were as follows: in the steady test, the film-forming solution was a pseudoplastic non-Newtonian fluid, and had the nature of Shear thinning, which could be fitted by Ostwald-de-Waele model. Meanwhile, the viscosity of film-forming solutions was increasing and the non-Newtonian ?ow behavior was becoming more obvious as the increasing content of sodium alginate, gum Arabic, plasticizer; the increasing temperature led to decreasing viscosity and the non-Newtonian ?ow behavior was first enhanced then weakened. In the dynamical test, storage modulus(G’)of film-forming solutions was first increasing then decreasing, and loss modulus(G’’)was increasing.Second, single factor test method and Box–Behnken design were employed to optimize the technology of preparing the edible films. Single factor test method was used to determine the ensile strength, elongation, WVP, water solubility of the films as affected by different amounts of sodium alginate, gum Arabic, plasticizer, drying temperature, the types and content of cross-linker. Based on this, Box–Behnken design with four factors at three levels was used. The best conditions were confirmed: the content of sodium alginate 3.24 %, the content of gum Arabic 0.58 %, the addition amount of plasticizer 0.50 g/100 ml, the addition amount of cross-linker 2.59 g/100 ml. Then ensile strength, elongation and water solubility of the film would be 63.74 Mpa, 3.18% and 1.53%.At last, ultraviolet spectrophotometer, FT-IR, SEM and DSC were used to research the compatibility of blend films. The results showed that sodium alginate/ gum Arabic blend films had a smooth surface, strong intermolecular interactions and good light transmission indicating that the compatibility of blend films was good. Thermal properties of different films were studied through DSC and TGA. The results showed that sodium alginate/ gum Arabic blend film and the one after cross-linking treatment had better thermal properties than pure film. The addition of plasticizer weakened the thermal properties.