Coating: Incorporation of laccase in pigment coating for bioactive paper applications

Novel and improved forest-based products are currently under intensive research and development. An interesting option is to add biomolecules into a pigment coating color and apply it on a paper surface. The aim of this work was to obtain general and profound knowledge about the effects of coating color composition and processing on the compatibility of the coating with biomolecules. Two different laccases, Trametes hirsuta (ThL) and Melanocarpus albomyces (MaL), having different redox potentials were studied as model biochemically active compounds in coating colors. Coating colors for LWC paper and inkjet paper were studied. The effects of coating color composition, pH, drying conditions of the coating layer and calendering on the enzymatic activity were studied. It was found out that laccase retained its activity in coating color dispersions as well as on the coated papers. MaL was found to retain its activity better in the coating layers than ThL. MaL had retained its activity in coated paper even after 5 ½ months storage. Drying of the coating layer did not reduce the enzyme activity significantly whereas calendering reduced the enzymatic activity to some extent.