1. Department of Food Science, Cornell University, Ithaca, New York 14853, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic and Center for Biomolecules and Complex Molecular Systems, Flemingovo nam. 2, 16610 Prague 6, Czech Republic, and Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, Grenoble Cedex 9 F-38042, France