1. Department of Health and Dietary Science, Research and Development Center, Nippon Meat Packers, Inc., 3-3 Midorigahara, Tsukuba-shi, Ibaraki 300-26, Japan
2. National Institute of Bioscience and Human Technology, Agency of Industrial Science and Technology, 1-1 Higashi, Tsukuba-shi, Ibaraki 305, Japan