1. Center for Agricultural Biomaterials, School of Agricultural Biotechnology, Seoul National University, Shillim-dong, Kwanak-gu, Seoul 151-742, Korea; Department of Food Science and Technology and Institute of Life Sciences and Resources, KyungHee University, Yongin 449-701, Korea; and Graduate School of Agriculture, Kyoto University, Goka-sho, Uji, Kyoto 611-0011, Japan