Xylan/chitosan composites prepared by an ionic liquid system with unique antioxidant properties

Antioxidant function and solubility in water are highly desirable in many applications of chitosan. In this paper, a xylan/chitosan composite was prepared in an ionic liquid system using glutaraldehyde as a crosslinking agent. The antioxidant activity, reducing capacity and metal ion chelating ability of the resulting composite were determined. The chemical structure and thermal stability were analyzed by FT-IR, XRD and TGA. The results showed that chitosan was successfully cross-linked with xylan by glutaraldehyde in the ionic liquid system. Compared to pure chitosan, the ABTS·+ scavenging activity of the xylan/chitosan composite increased from 10.56% to 97.59%. After cross-linking with xylan by glutaraldehyde, the reducing power of xylan/chitosan composite increased from 0.054 to 2.109. The capacity of chelating metal ion of the composite also increased from 42.35% to 86.71% compared to that of pure chitosan. An underlying mechanism was proposed to account for the improvement of the chemical properties of the chitosan in the composite.