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

Hymenaea courbaril var courbaril seed xyloglucan was efficiently extracted with 0.1 M NaCl, followed by ethanol precipitation (yield = 72 ± 5% w/w). Its amorphous structure was identified by the pattern of X-ray diffraction. The monosaccharide composition was determined by GC/MS analysis of the alditol acetates and showed the occurrence of glucose:xylose:galactose:arabinose (40:34:20:6). One-(1D) and two-dimensional-(2D) NMR spectra confirmed a central backbone composed by 4-linked β-glucose units partially branched at position 6 with non-reducing terminal units of α-xylose or β-galactose-(1→2)-α-xylose disaccharides. The xyloglucan solution was evaluated by dynamic light scattering and presents a polydisperse and practically neutral profile, and at 0.5 and 1.0% (w/v) the solutions behave as a viscoelastic fluid. The polysaccharide did not show significant antibacterial or hemolytic activities. Overall our results indicate that xyloglucan from H. courbaril is a promising polysaccharide for food and pharmaceutical industries.