Fabrication and characterization of glycerin-plasticized soy protein amyloid fibril scaffolds by unidirectional freeze casting method

Soy protein amyloid fibrils (SAFs) plasticized with glycerin were prepared into aligned porous scaffolds through the unidirectional freeze casting method. The impact of the amount of glycerin on the structural and functional properties of the SAFs-Gly scaffolds was investigated. Scanning electron microscopy confirmed that the aligned pore size and distribution of the scaffolds, with diameters ranging of 10-50 mu m, could be adjusted by varying the amount of glycerin. Increasing the glycerin content decreased the median pore size of the scaffolds and increased the strain at the yield point by up to 40%. Additionally, the water resistance of the scaffolds significantly increased without any obvious changes in morphology. Differential scanning calorimetry analysis revealed two glass transitions in the SAFs/glycerin systems, corresponding to the glycerin-rich and protein-rich domains, respectively. FTIR spectroscopy indicated the formation of hydroxyl interactions and intermolecular hydrogen bonding between SAFs and glycerin. X-ray diffraction and small-angle X-ray scattering suggested that glycerin can induce SAFs crystallization, structural separation, and exfoliation of beta-sheets to some extent. These results demonstrate the prospective application of this approach in the preparation of food-based polymer scaffolds and its usefulness in the food industry.