Extraction and physicochemical characterization of galactomannans from Dichrostachys cinerea seeds

Water soluble seed polysaccharide from Dichrostachys cinerea seeds were extracted and characterized by several techniques such as SEM, GC-MS, attenuated total reflection Fourier Transform Infrared spectroscopy (ATR-IR), thermogravimetric differential Thermal analysis (TGDTA), XRD and viscosimetry, the final yield was 21 %. Methylation and GC-MS analysis confirmed the linkage profile of galactomannan a 4-linked mannose polymer with galactose side chains attached at the C6 position. It has an estimated average degree of polymerization of 450 and a degree of branching of 0.65. The powder morphology was visualized using SEM. ATR-IR analysis showed the complexity of the polysaccharide. The XRD confirmed the crystallinity and amorphous nature of the polysaccharide, while TGDTA spectra showed the presence of three peaks weight loss events and decomposition patterns. The polysaccharide had an average intrinsic viscosity of 3.42 dl/g. These results showed that the extracted polysaccharides are typically amorphous, thermally stable and might be expected to have wide applications in food and pharmaceutical industries.