Characterization and rheological study of the galactomannan extracted from seeds of Cassia grandis

Abstract

Galactomannan extracted from seeds of Cassia grandis with 0.1M NaCl, followed by ethanol precipitation, presented a yield of 36 ± 8%. The polysaccharide has a constant mannose/galactose ratio (2.44:1). Methylation analysis, one and two dimensional NMR spectroscopy confirmed that the polysaccharide 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. The amorphous nature of the galactomannan was confirmed by X-ray diffraction. Rheological characterization exhibited Newtonian plateaus followed by shear-thinning zones characteristic of polymer solutions up to 1.5% (w/v) and above this value the system exhibited yield stress associated with a weak gel. Adjusting stress-strain curves confirmed a 1.6% (w/v) as the galactomannan concentration value for the sol-gel transition. These results indicate that the galactomannan extracted from C. grandis seeds presents rheological characteristics suitable for applications in pharmaceutical, biomedical, cosmetic and food industries.

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

“…The signals observed and the general pattern of the spectrum are consistent with a backbone constituted by (1 / 4)-linked b-D-mannopyranosyl (b-D-Manp) residues with single stubs of a-D-galactopyranosyl (a-D-Galp) units, attached at C-6. This spectrum is in agreement with those reported for galactomannans with the same substitution pattern (Albuquerque et al, 2014;Chaubey & Kapoor, 2001;Cheng & Neiss, 2012;Kapoor et al, 1998;Manzi & Cerezo, 1986;Muschin & Yoshida, 2012).…”

Rheological properties of a β-1,3-polyglucuronic acid derivative from 4-acetamido-TEMPO-mediated oxidation of curdlan

“…35 Such association may subsequently lead to formation of weak networks in the aqueous solution because of strong interactions between carboxylic curdlan molecules. Similar results have been observed for galactomannan, 36 exopolysaccharides from the fermentation medium of a Cordyceps sinensis fungus Cs-HK1, 37 tara gum, 29 and curdlan in DMSO, 23 among others. Therefore, based on the above results, the mechanical spectra of carboxylic curdlan solution might be classied as a dilute solution (<1.0%, w/v), entanglement network (2.0%, w/v), and weak gel (4.0%, w/v or above).…”

Structure and rheological properties of a xyloglucan extracted from Hymenaea courbaril var. courbaril seeds

“…The xyloglucan from the seeds of H. courbaril was obtained by the method of Albuquerque et al (2014) [14]. The seeds were manually removed from dry pods, washed and boiled in distilled water at 100 • C for 30 min for enzyme inactivation and softening of the hulls.…”