1. Research Centre Applied Biocatalysis, Petersgasse 14, A-8010 Graz, Austria, Division of Food Biotechnology, Department of Food Sciences and Technology, University of Natural Resources and Applied Life Sciences Vienna, Muthgasse 18, A-1190 Vienna, Austria, and Lactoprot Alpenländische Milchindustrie und Handels GmbH, Ferdinand-Leihs-Strasse 40, A-8230 Hartberg, Austria