1. Lehrstuhl für Allgemeine Lebensmitteltechnologie, Technische Universität München, Am Forum 2, D-85350 Freising-Weihenstephan, Germany, and IAEA-Zhejiang University Collaborating Center, Key Laboratory of Chinese Ministry of Agriculture for Nuclear-Agricultural Sciences, Institute of Nuclear Agricultural Sciences, Zhejiang University, Hangzhou 310029, China