1. Wageningen Centre for Food Sciences1 and Food and Bioprocess Engineering Group,2 Wageningen University, PO Box 8129, 6700 EV Wageningen, The Netherlands
2. NIZO Food Research, PO Box 20, 6710 BA, Ede, The Netherlands3
3. BioCentrum Amsterdam, Dept of Molecular Cell Physiology, Free University, De Boelelaan 1087, NL-1081 HV Amsterdam, The Netherlands4
4. Dept of Biochemistry, University of Stellenbosch, Private bag X1, Matieland 7602, Stellenbosch, South Africa5