1. College of Chemical and Pharmaceutical Engineering, Hebei University of Science and Technology, Shijiazhuang, Hebei Province 050018, P. R. China
2. Yanjing Beer (Guilin Liquan) Company, Ltd., Guilin, Guangxi Province 541000, P. R. China
3. School of Chemical Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia