Department of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, Ås, P.O. Box 5003, N-1432, Norway.|Department of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, Ås, P.O. Box 5003, N-1432, Norway.|Department of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, Ås, P.O. Box 5003, N-1432, Norway. lars.snipen@nmbu.no.