1. Laboratory of Food Chemistry, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands; Nippon Del Monte Corporation, 3748 Shimizu-cho, Numata, Gunma, 378-0016 Japan; and Wageningen NMR Centre, Wageningen University, P.O. Box 8128, 6700 ET Wageningen, The Netherlands