1. Morinaga & Company, Ltd., 2-1-1 Shimosueyoshi, Tsurumi-ku, Yokohama 230-8504, Japan
2. National Institute of Vegetable and Tea Science, National Agriculture and Food Research Organization, 2769 Kanaya, Shimada, Shizuoka 428-8501, Japan
3. The Graduate School of Bioresources and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku Fukuoka812-8581, Japan