Bacillus subtilis natto fermentation to improve aglycone isoflavones content of black soybean varieties detam 2

The utilization of Bacillus subtilis natto (B.natto) in fermentation was expected to increase the content of aglycone isoflavones which is beneficial for health. This study aimed to measure the isoflavone aglycone daidzein and genistein content in fermented black soybean varieties detam 2 using B. natto strain IFO 3335. HPLC analysis on aglycone showed that 100 g dry weight of defatted raw soybean sample contained 1.29 mg and 1.16 mg of genistein and daidzein respectively, while undefatted raw soybean sample contained 1.19 mg and 1.07 mg. After fermentation, both genistein and daidzein concentration increased up to 8 times as much as those in the raw soybean. After fermentation, genistein concentration was measured 10.43 mg (defatted) and 9.43 mg (undefatted) one while daidzein concentration was 9.60 mg (deffated) and 8.68 mg (undefatted) one. Thus, fermentation using Bacillus subtilis natto was proven to improve the content of genistein and daidzein in black soybean varieties detam 2.