Changes in isoflavone content and quality characteristics of Cheonggukjang prepared with Bacillus subtilis HJ18-3 and KACC 15935

This study was conducted in order to investigate the change of isoflavone composition (glycoside and bio-active aglycone), and to evaluate the quality characteristics of Cheonggukjang, which was prepared by different bacillus strains. After the 48-hour fermentation, the contents of daidzein, genistein, and glycitein in the Bacillus subtilis HJ18-3 have significantly increased up to approximately 89.06±3.59, 10.36±0.28, and 101.37±3.67 ug/g, respectively. The contents of daidzein, genistein, and glycitein in the Bacillus subtilis KACC 15935 were 38.88±5.39, 12.58±2.14, and 80.13±0.71 ug/g, respectively. The original content of daidzein was 3.96 ug/g, while genistein and glycitein were not measured. However, the contents of daidzen and genistein in HJ18-3 and in KACC 15935 were decreased. The α-Amylase and cellulase activities of Chungkookjang in HJ18-3 were higher than in the KACC 15935. The contents of Chungkookjang in HJ18-3 were 29.70±11.66 and 4861.3±388.07 unit/g, respectively. The amino type nitrogen contents and ammonia type nitrogen contents of Chungkookjang in KACC 15935 were higher than in the HJ18-3. These results suggested that it could be used to increase the bioactivity via fermentation with the Bacillus subtilis possessing a β-glucosidase activity with a view towards the development of functional foods.