1. Centre for Malting and Brewing Science, Faculty of Bioscience Engineering, Catholic University of Leuven, Kasteelpark Arenberg 22 box 02463, 3001 Heverlee, Belgium, Brasserie d’Orval S.A., 6823 Villers-devant-Orval, Belgium, and Brewery Duvel Moortgat N.V., Breendonkdorp 58, 2870 Puurs, Belgium