1. College of Enology; Northwest A&F Univ; Yangling Shaanxi 712100 China
2. Food Science and Human Nutrition Dept., Inst. of Agricultural and Food Sciences; Univ. of Florida; Gainesville Fla. 32611 U.S.A
3. Center for Brewing Science and Enzyme Biotechnology, School of Biotechnology; Jiangnan Univ; Wuxi Jiangsu 214122 China