1. Laboratory of Food Chemistry and Biochemistry and Leuven Food Science and Nutrition Research Centre (LFoRCe), Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium.
2. Corresponding author. Phone: +32 (0) 16321575. Fax: +32 (0) 16321997. E-mail: bram.pareyt@biw.kuleuven.be