1. Department of Food Technology and Nutritional Science, Food Science Group, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands, Department of Physical and Colloid Chemistry, Wageningen University, P.O. Box 8038, 6700 EK Wageningen, The Netherlands, and Department of Molecular Physics, Wageningen University, P.O. Box 8128, 6700 ET Wageningen, The Netherlands