1. TI Food and Nutrition, P.O. Box 557, 6700 AN Wageningen, the Netherlands
2. Wageningen University and Research Centre, Laboratory of Food Microbiology, P.O. Box 8129, 6700 EV Wageningen, the Netherlands
3. Universidad de Zaragoza, Food Technology Group, Miguel Servet 177, 50013 Zaragoza, Spain
4. Wageningen University and Research Centre, Food Technology Centre, P.O. Box 17, 6700 AA Wageningen, the Netherlands