Influence of extraction conditions on properties of seed xyloglucan

Abstract

Xyloglucans are water-soluble polysaccharides that serve as storage in cotyledonary tissues from seeds of Hymenaea courbaril among other Leguminosae. The use of xyloglucans is dependent on their solution properties. We now examine the influence of different times of extractions on its properties. Xyloglucans were obtained from milled and defatted cotyledons of H. courbaril by aqueous extraction at 25 degrees C for 0.25, 0.5, 1, 5, 15, 24, and 48 h. Composition data showed that increase in time lead to the increased protein contamination and arabinose content. Xyloglucans obtained with longer times of extraction had an average molar mass greater than those obtained with shorter times. The hydrodynamic radius and the radius of gyration also increased with the increase in the time of extraction. The ratio R(g)/R(h) was calculated and the values decreased slightly for increasing times of extraction. The effect of time also affected the viscosity which increased with the increase in time of extraction, and the longer ones probably contributing to the aggregation of xyloglucans.

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

“…The branching pattern of xyloglucan from different plant species was evaluated and demonstrated that some xyloglucans have an additional arabinose unit linked to the galactose residues at the non-reducing end of the side chain [31]. Kay & Petkowicz [25] suggest that the presence of arabinose is due to co-purified arabinan, which corroborates our result. They also confirmed the absence of arabinose residues in shorter extraction processes, while others workers [3,11] described arabinose traces in xyloglucans from seeds.…”

“…No signals ascribed to non-reducing ␤-arabinofuranosyl units were observed at 109/5.3 ppm. This type of residue was reported in other plant polysaccharide [25]. They may occur only in minor amounts in our xyloglucan preparation and not detected on the NMR spectrum.…”

“…For a xyloglucan solution 0.5% (w/v) at pH 5.8, Z-average and PDI were 296.00 ± 12.40 nm and 0.32 ± 0.02, respectively, indicating a reasonably polydisperse solution. Z-averages values of 170 nm [24] and 80 nm [25] were reported for xyloglucan from H. courbaril seeds at 1 mg mL −1 , which are lower concentrations than ours (0.5% w/v), as well as the different method for extraction.…”

“…Different extraction times for xyloglucan were compared and demonstrated a variation of yield from 5.4 to 40.8% [25]. However, these authors did not mention clearly if your yield are related to moist or dry weight of the seeds.…”

“…This variation is a consequence of interspecific variations [3] and also of the extraction methods [25].…”