1. Food Chemistry, Faculty of Mathematics, Informatics and Natural Sciences, University of Hamburg, Grindelallee 117, D-20146 Hamburg, Germany; AG Proteomics, Max-Planck-Institute of Experimental Medicine, Hermann-Rein-Strasse 3, D-37075 Göttingen, Germany; and Nestlé Research Center, P.O. Box 44, 1000 Lausanne 26, Switzerland