Effects of extrusion on structural and physicochemical properties of soluble dietary fiber from nodes of lotus root

Effects of extrusion on the structural and physicochemical properties of soluble dietary fiber (SDF) from non-extruded and extruded powders of lotus root nodes were investigated by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), gas chromatography (GC) and rheological analysis. Results showed that extrusion affected the microstructure and molecular size of the node powder and SDF powder, leading to degradation of cellulose and hemicellulose in the dietary fiber as well as changes in monosaccharide composition and sugar ratio. Extrusion also improved SDF hydration properties such as swelling capacity, waterholding capacity and emulsibility. The overall results indicate that the structural and physicochemical properties of the dietary fiber were enhanced by the extrusion treatment.