1. Department of Ornamentals, Danish Institute of Plant and Soil Science, Kirstinebjergvej 10, DK-5792 Aarslev, Denmark, Department of Food Science and Technology, Danish Institute of Plant and Soil Science, Kirstinebjergvej 12, DK-5792 Aarslev, Denmark, and Department of Chemistry, Odense University, DK-5230 Odense M, Denmark