Relationship between the viscoelastic, structural and microstructural characteristics of highly ferulated...

The viscoelastic, structural, and microstructural characteristics of arabinoxylans (AX) gels depend on the polysaccharide's structure. Higher ferulic acid (FA) contents result in stronger AX gels with greater cross-links and more compact microstructures. This work aimed to conduct a deeper theoretical analysis of the structural characteristics of highly cross-linked AX gels and to establish a relationship with their viscoelastic and microstructural characteristics. Previously characterized highly ferulated AX (5.46 μg/mg AX) formed strong gels (G' = 227 Pa) with a highly cross-linked structure (di-FA = 1.62 μg/mg AX) and a compact microstructure. The distribution of FA residues in the polysaccharide chain was less spaced in the AX (55 nm between two FAs) compared to the AX gel (83 nm between two FAs) due to the oxidation of the FA during the gelling process. The distance between two di-FA decreased from 1658 to 358 nm after gelation, indicating increased cross-linking content. The results demonstrate that AX with highly ferulated structures forms highly cross-linked gels where di-FA distribution within the polymer chains is more frequent. This distribution of cross-links in the polymeric network is reflected in more elastic gels exhibiting more compact microstructures.