Degalatosylation of xyloglucan: Effect on aggregation and conformation, as determined by time dependent static light scattering, HPSEC–MALLS and viscosimetry

Degalactosylation of xyloglucan from the seeds of Hymenaea courbaril by β-galactosidase, which strips the (1 → 2)β-d-galactose side groups, was monitored in real time using time dependent static light scattering (TDSLS), viscosimetry and HPSEC–MALLS. The galactose side-chain stripping rate constant (α) was determined by TDSLS as 1.3 × 10−6 s−1 and the scattering at 90° showed a little upwards curvature, indicating a high fraction of mass in the backbone (fp 0.78). There was an increase in aggregation during degalactosylation, especially during later stages, resulting in a microgel at dilute concentrations. Lp was determined using viscosimetric techniques in order to avoid the influence of aggregates. A value of approximately 4 nm was obtained, both before and after enzymatic hydrolysis. The results confirm that aggregation is the principal phenomenon responsible for gelling of degalactosylated xyloglucan and that the conformation is practically unaffected during the enzymatic treatment.