Molecular structural properties of a polysaccharide isolated and purified from Sophora japonica pods and its relationship to their rheology

A water-soluble polysaccharide SJ-A presenting a relatively narrow molecular weight distribution was prepared by ethanol precipitation and purified from the pods of S. japonica. Chemical composition, molecular weight distribution, and glycosidic configurations of SJ-A were elucidated by sugar analysis, molecular determination, Fourier-transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR) analyses. The impacts of the concentration (0.5-2.0%) of SJ-A on the rheological parameters were investigated to clarify the molecular crosslinking features of SJ-A in relation to its rheological properties. The experimental results indicated that the microstructural coupling of the gel induced at higher concentrations of SJ-A required a higher frequency of the rheometer.