1. Department of Bioengineering, the University of Tokyo, 1-3-7 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
2. Department of Electric Engineering and Information Systems, The University of Tokyo, 1-3-7 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
3. Food Research Institute, National Agriculture and Food Research Organization, 2-1-12, Kannondai, Tsukuba, Ibaraki 305-8642, Japan