Extraction, purification and characterization of galactomannans from non-traditional sources

This work presents a methodology for the extraction of galactomannans from seeds of four different species of Leguminosae (Adenanthera pavonina, Caesalpinia pulcherrima, Gleditsia triacanthos and Sophora japonica) to be used e.g. in the food and biomedical industries. The galactomannans were obtained by aqueous extraction followed by a precipitation with ethanol. This methodology is simpler and easier to perform than other existing extraction and purification methodologies, and because it avoids the use of organic solvents (other than ethanol), it is able to generate food grade substances and is environmentally friendlier. The yield of extraction in different stages of the process, monosaccharide composition, as well as physical and chemical parameters of the isolated galactomannans were determined and compared with previously published results. The mannose/galactose ratio of the extracted galactomannans ranged from 1.35 (A. pavonina) to 5.75 (S. japonica). The intrinsic viscosity ranged from 11.34 dL/g (C. pulcherrima) to 8.74 dL/g (S. japonica), while the viscosity average molecular mass ranged between 1.81 × 106 Da and 1.17 × 106 Da (A. pavonina > C. pulcherrima > G. triacanthos > S. japonica). The results confirm the suitability of the extraction and purification procedure to obtain galactomannans from non-traditional sources.