Institute of Nutritional Science, Chair of Food Science, and TransMIT Center for Effect-Directed Analysis, Justus Liebig University Giessen, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany; On leave from Università degli Studi di Milano, Facoltà di Scienze Agrarie e Alimentari, Via Giovanni Celoria 2, 20133 Milano, Italy.