Enzymatic cross-linking of ferulated arabinoxylan: effect of laccase or peroxidase catalysis on the gel characteristics.

Abstract

Arabinoxylans (AX) gels at 4% (w/v) were prepared using laccase (LAX gels) or peroxidase (PAX gels), and their cross-linking, rheological, structural, and spectroscopic characteristics were investigated. LAX gels presented lower amount of 5,5'-diferulic acid (11%), smaller mesh size (128nm), and higher hardness (37N) and elasticity (430Pa) than the PAX gels (28%, 197nm, 7N, and 120Pa, respectively). Microscopy of the LAX gels showed linked strands, while the system was less connected in the PAX gels. The Raman band at 2895cm-1 of the LAX and PAX gels was less intense, indicating enhanced hydrogen bonding compared to that of AX. This decrease was less dramatic for the PAX gels. The greater content of 5,5'-diferulic acid in PAX gels could favor intrachain bonds, affecting their rheological, structural, and spectroscopic characteristics. Laccase may be a better option than peroxidase for AX gelation intended for food and biotechnological applications.