Morphology and mechanical properties of soy protein scaffolds made by directional freezing

Directional freezing and freeze-drying techniques were used to make robust soy protein scaffolds. The development of the morphology and mechanical properties of the scaffolds with fabrication conditions such as solution concentration and freeze temperature was studied in detail. Directional freezing produced anisotropic morphological features in the soy protein scaffolds, which produced differences between the mechanical properties in the freeze direction and the direction perpendicular to it. The evolution of the scaffold morphology started from the fibrillar columns, which widened to become layers and which then grew regularly spaced ridges normal to the layers, which eventually fused to form a highly anisotropic foam structure. Suitable soy protein solutions for making the scaffolds were prepared with guanidine hydrochloride and dithiothreitol, and the viscosity-concentration relations showed that the soy protein behaved consistently as a good polymer solution over the concentration range used for the scaffolds.