Vinal gum, a galactomannan from Prosopis ruscifolia seeds: Physicochemical characterization

Physico-chemical and rheological characterization of the gum extracted from the endosperm of vinal (Prosopis ruscifolia) seeds was performed. The CG-MS analysis revealed that vinal gum is a galactomannan with a mannose/galactose ratio of 1.6, with traces of arabinose and glucose residues. The structure was further confirmed by C-13 NMR which showed several similarities between vinal gum and guar gum spectra. The viscosity molecular weight was 1.43 +/- 0.04.10(6) Da (obtained from Huggins plot) and the average number molecular weight was 0.7.10(5) Da. Shear continuous rheology studies showed a shear thinning behavior at concentrations higher than 0.04% (w/v) of vinal gum and an apparent viscosity slightly lower than that of guar gum at the same concentration. Mechanical spectra revealed that vinal gum has a typical macromolecular solution behavior with the moduli crossing point that characterized semi-diluted (0.16-0.3% w/v) gum solutions. The present work provides structural, physicochemical and rheological information of a new galactomannan from an abundant and available non-traditional source, being a starting point for food, pharmaceutical or other industrial potential applications of vinal gum. (C) 2015 Elsevier Ltd. All rights reserved.