1. DLO State Institute for Quality Control of Agricultural products (RIKILT-DLO), Bornsesteeg 45, NL-6708 PD Wageningen, The Netherlands
2. National Institute of Public Health and Environmental Protection, P.O. Box I, NL-3720 BA Bilthoven, The Netherlands
3. Agricultural University, Department of Human Nutrition, Bomenweg 2, NL-6703 HD Wageningen, The Netherlands