ABSTRACT
The aim of this research was to investigate the cross-linking content, rheo-logical, and structural characteristics of water-extractable arabinoxylans (WEAX) and water-unextractable arabinoxylans (WUAX) gels. The intrinsic viscosity, viscosimetric mass and ferulic acid (FA) content were 3.6 and 2.1 dL/g, 440 and 74 kDa and 0.40 and 0.08 μg/mg polysaccharide, for WEAX and WUAX, respectively. The Fourier transform infrared spectrum of WEAX and WUAX presented characteristics bands (1035, 1158 and 897 cm−1) related to β(1–4) linkages. WEAX and WUAX laccase induced gels at 3% (w/v) registered a di-FA content of 0.076 and 0.008 μg/mg polysaccharide, respectively. Storage (G’) and loss (G”) moduli were 101 and 20 Pa for WEAX gel and 174 and 19 Pa for WUAX gel. The structural parameters of WEAX and WUAX gels were calculated from swelling experiments. WEAX and WUAX gels mesh size were 123 nm and 48 nm, respectively. As di-FA content was lower in WUAX gels, a more important contribution of physical interactions between polysaccharide chains and/or non-identified ferulate cross-linking structures could be responsible of these rheological and structural differences between WEAX and WUAX gels.
