1. Department of Applied Chemistry and Microbiology, P.O. Box 27 (Latokartanonkaari 11), FIN-00014 University of Helsinki, Finland; Department of Food Chemistry and Technology, Graz University of Technology, Petersgasse 12/2, 8010 Graz, Austria; and Department of Chemistry, P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014 University of Helsinki, Finland