1. Department of Agricultural Biotechnology and Center for Agricultural Biomaterials, Seoul National University, Seoul 151-921, Korea.
2. Department of Food Science and Technology, Sejong University, Seoul 143-747, Korea.
3. Corresponding author. Phone: +82-2-880-4854. Fax: +82-2-873-5095. E-mail: twmoon@snu.ac.kr