Facile and green preparation of diverse arabinoxylan hydrogels from wheat bran by combining subcritical water and enzymatic crosslinking

Abstract

Feruloylated arabinoxylans demonstrate great potential in developing natural materials through oxidative crosslinking. However, the common alkaline method to extract arabinoxylans causes heavy losses of feruloyl esters thus hinders the crosslinking activity. Highly feruloylated arabinoxylans were fractionated from wheat bran by an alternative method using subcritical water extraction (SWE) and were compared with water- and alkali-extracted arabinoxylans. Various yields, chemical compositions, and molecular weights were obtained as the SWE conditions changed. Methylation analysis showed that the SWE arabinoxylans had a similar linkage pattern as the water-extracted arabinoxylan. Laccase-induced oxidative crosslinking was investigated through dynamic rheology, finding a broad spectrum of gelling ability for the SWE arabinoxylans. Finally, the optimal condition (160 °C, pH 7 for 10 min) was used in a repeated SWE procedure to maximize the yield and crosslinking properties. The combination of subcritical water and enzymatic crosslinking presents as a promising green approach for preparing hydrogels from herbaceous hemicelluloses.