1. Department of Chemistry, Tokyo Metropolitan University, 1-1 Minami-Ohsawa, Hachioji, Tokyo 192-0397, Japan, FLW, Food Research & Development Laboratories, Ajinomoto Co., Inc. 1-1, Suzuki-cho, Kawasaki-ku, Kawasaki-shi 210-8681, Japan, and Water Research Institute, Sengen 2-1-6, Tsukuba, Ibaraki 305-004, Japan