1. Institute of Food Technology, Section Plant Foodstuff Technology, Hohenheim University, August-von-Hartmann-Strasse 3D-70599 Stuttgart, Germany, Chemisches und Veterinäruntersuchungsamt Stuttgart, Schaflandstrasse 3/2, D-70736 Fellbach, Germany, Institute of Crop Farming and Grassland Research, Hohenheim University, Fruwirthstrasse 23, D-70599 Stuttgart, Germany, and Experimental Station Ihinger Hof, Hohenheim University, D-71272 Renningen, Germany