Functionalization of chitosan by laccase-catalyzed oxidation of ferulic acid and ethyl ferulate under heterogeneous reaction conditions

► Chitosan was functionalized as solid particles with phenolic compounds. ► Phenolic acids were grafted onto chitosan thanks to laccase catalysis. ► Covalent bonds were proved between oxidative products and free amino groups of chitosan. ► Chitosan derivatives presented improved functional properties. ► The grafting, an eco-friendly procedure, is performed in aqueous medium.