1. Department of Food and Environmental Sciences, P.O. Box 27, 00014 University of Helsinki, Finland
2. VTT Technical Research Centre of Finland, P.O. Box 1000, 02044 VTT, Finland
3. Department of Biosciences, P.O. Box 56, 00014 University of Helsinki, Finland
4. Plant Products and Food Quality Programme, Scottish Crop Research Institute, Dundee DD2 5DA, Scotland, U.K.