Characterization and comparative studies of galactomannans from Bauhinia vahlii, Delonix elata, and Peltophorum...

The present investigation determines the extraction and characterization of seed galactomannans from the Leguminosae taxa of Bauhinia vahlii, Delonix elata, and Peltophorum pterocarpum. The seed galactomannans presented a total yield of 30.82, 24.01 and 25.25% with a Man/Gal ratios of 4.21:1, 2.55:1 and 3.03:1 for B. vahlii, D. elata, and P. pterocarpum, respectively exhibiting 1-4 mannose linkages with galactose side chains at C6 position. The galactomannans presented an efficient water holding capacity, solubility and emulsion properties. Intrinsic viscosity from combined Huggins and Kraemer extrapolations are 3.807, 3.424 and 3.331 dl g^-1 and the viscosity average molecular weight by Mark-Houwink relationship are 5.29 × 10⁵, 5.29 × 10⁵ and 4.95 × 10⁵ for B. vahlii, D. elata, and P. pterocarpum, respectively. TEM analysis of the polysaccharide showed an aggregated amorphous smooth particles, oval or tubular in shape, branched with compact surfaces. SEM micrographs of the powdered galactomannan indicate well defined amorphous material with pores and cervices on the rough surface. The thermal property studied by DSC and TG-DTA suggests good thermal stability. These findings demonstrate that the seed galactomannan of B. vahlii, D. elata, and P. pterocarpum could be explored as an effective alternative to commercial galactomannans for industrial applications.