Commercially available soybean seeds (yellow-soybean, Tamahomare and black-soybean, Sakushuu-kuro) harvested
in Okayama prefecture, Japan, were used in this study. The yellow-soybean tempeh and black-soybean tempeh were produced by Ukan-Farmers-Factory (Okayama). The defatted-soybean germ and defatted-soybean cotyledon from
the yellow-soybean made in USA were provided by KatohSeiyu (Okayama). Rhizopus sp., a mold used for tempeh
fermentation, was purchased from Akita-Konno (Akita). Tempeh made of soybeans or their particular tissues was
produced as previously described (9). The contents of 12 different derivatives of isoflavone (three types of isoflavone aglycon and the corresponding nine types of isoflavone-glucoside) in tempeh (per 100 g, wet) were determined by
HPLC according to a previously reported method (11) using 10 µl of tempeh extract obtained with 70% (v/v) methanol
under the following conditions: YMC-Pack column, ODSAM-303 (φ4.6×250 mm); compositions of solvent A, acetonitrile:H2O:acetic acid = 15:85:0.1 (v/v/v) and solvent B, acetonitrile:H2O:acetic acid = 35:65:0.1 (v/v/v); gradient elution, 15–35% acetonitrile/60 min; flow rate, 1 ml/min; detection at 254 nm. Twelve derivatives of isoflavone provided by Fujicco (Kobe) were used as standards