Conferring antioxidant capacity to cellulose based materials by using enzymatically-modified products

A new, industrially feasible method for conferring cellulosic substrates antioxidant properties by using enzymatic products was developed. The method allows cellulose surfaces such as those of paper sheets to be conferred antioxidant capacity by using a functionalization solution (FS) obtained from an enzymatic reaction. Various laccases and different phenolic compounds (PhCs) potentially possessing antioxidant action were used to prepare the FS. Antioxidant capacity was assessed by using UV spectrophotometry to monitor the inhibition of ABTS radical cation (ABTS·⁺) in the presence of antioxidants. Based on the results, enzymatic modification of the phenolic compound in the FS increases the bonding strength of its components to cellulosic materials. Evidences on the grafting of the FS onto the cellulosic sheets, and changes in the chemical structure of the resulting oxidized form of PhCs were assessed by using ATR–FTIR. The level of antioxidant capacity achieved depends on the enzyme type, the chemical structure of the compounds in FS, and the presence of lignosulfonates in it. The potential of the proposed method for conferring antioxidant properties to cellulose-based materials by surface application of a product obtained from an enzymatic reaction is demonstrated here for the first time.