Characterization of Galactomannan Isolated from Algerian Gleditsia triacanthos L. Seeds

Background: The galactomannans are water-soluble carbohydrates widely used in the food, pharmaceutical, biomedical, cosmetic, textile and paper industries. Recently, a need for an alternative industrial source of galactomannans has arisen; one possible source is Honey locust (Gleditsia triacanthos), which is abundant in Algeria. Objective: The main objective of this study was to determine the physicochemical and rheological properties of Water-Soluble Galactomannan (WSG) purified from the seeds of Algerian Honey locust (Gleditsia triacanthos L.). Methods: The galactomannan was purified from the seeds of Gleditsia triacanthos and was structurally characterized by chromatographic (HPAEC, HPSEC-RID-MALLS) and spectroscopic (FT-IR, 1H, 13C NMR) methods. Results: The Honey locust seed contains a high level of WSG (yield, 10%), and the molecular weight of its WSG was approximately 871.9 kDa. A highly viscous solution was obtained and had an intrinsic viscosity [η] of 7.14-7.25 dL/g and an optical activity [α]D of +38.7°. Chromatographic and spectroscopic analyses indicated the presence of β-D-mannopyranose and α-D-galactopyranose in the heteropolysaccharide at a molar ratio of 2.86:1. The linear backbone of its macromolecule has a central core composed of 4-linked β-mannose units, with branches of galactose, linked to the carbohydrate core through α(1-6) linkage. Conclusion: These results lead to the conclusion that galactomannan presents the desirable physicochemical characteristics suitable for applications in the pharmaceutical, cosmetic and food industries.