Rheological properties of thermally xyloglucan gel from the seeds of Hymenaea courbaril

A Brazilian source of galactoxyloglucan was obtained from seeds of Hymenaea courbaril and investigated before (JN) and after the hydrolytic removal of galactose (JH). The native polysaccharide contained glucose, xylose and galactose in a ~ 4.0:2.7:1 molar ratio. Gelation occurred when ~ 51% of the galactose residues was removed from the xyloglucan by fungal β-galactosidase. The rheological properties of JN and JH were analyzed. Dynamic oscillatory measurements characterized JN as a viscoelastic solution and JH as a true gel. JH achieved the maximum storage modulus G′ at temperatures above 40 °C and was found to increase with the increasing concentration. The gel point temperatures of JH fraction were determined at the cross-over point of G′ and G″ and by calculating the inflexion point of the G′ plot.