1. Department of Biotechnology and Chemical Technology, Faculty of Chemistry and Material Sciences, Helsinki University of Technology, P.O. Box 6100, FIN-02015 TKK, Finland, Department of Forest Products Technology, Faculty of Chemistry and Material Sciences, Helsinki University of Technology, P.O. Box 6300, FIN-02015 TKK, Finland, and SciTech Service Oy Ltd., Tekniikantie 12, Innopoli 1, FIN-02150 Espoo, Finland