1. National Research Institute of Vegetables, Ornamental Plants and Tea, Ministry of Agriculture, Forestry and Fisheries, 2769 Kanaya, Shizuoka 428-8501, Japan; Food Research Laboratories, Mitsui Norin Company, Ltd., Miyahara 223-1, Fujieda, Shizuoka 426-0133, Japan; and School of Food and Nutritional Sciences, University of Shizuoka, Yada, Shizuoka 422-8526, Japan