1. Lab. of Food Chemistry, Graduate School of Agriculture and Biological Sciences, Osaka Prefecture University, 1-1, Gakuen-cho, Sakai, Osaka 599-8531, Japan.
2. Present address: Department of Life and Health Sciences, Hyogo University of Teacher Education, 942-1, Shimokume, Yashiro, Hyogo 673-1494, Japan.
3. Division of Research and Development, Daiwa Kasei K. K., 4-19, Hie-cho, Kosei-cho, Koka, Shiga 520-3203, Japan.
4. Corresponding author. Phone: +81-72-254-9459. Fax: +81-72-254-9921. E-mail: morita@biochem.osakafu-u.ac.jp.