Characteristics and increased antimutagenic effects of black soybean chungkukjangs fermented by
Bacillus subtilis were determined. Var. seoritae (large size black soybean) chungkukjang (SR-BSC)
induced higher growth rate of total viable counts during the fermentation at 40oC for 3 days, and the
fermentation pattern was almost same as typical chungkukjang fermented with var. hwangkeumkong
soybeans. The NH2-N and NH3-N contents in SR-BSC were the same levels found in the var. hwangkeumkong
soybean chungkukjang (HK-SC), but exhibited higher level of γ-GTP. Sensory evaluation
test of SR-BSC also showed highest overall acceptibility. The mutagenicities induced by aflatoxin B1
(AFB1) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were significantly inhibited by the methanol
extract of SR-BSC compared to typical chungkukjang prepared with var. hwangkeumkong soybean and
var. seomoctae (small size black soybean) chungkukjang (SM-BSC). SR-BSC contained highest levels
of isoflavones among the tested chungkukjangs. The contents and composition of various isoflavones
of chungkukjang were evaluated. The total isoflavone contents of SR-BSC, SM-BSC and HK-SC were
3688.9, 698.6 and 2764.6μg/g, respectively. In SR-BSC, the levels of aglycones of genistein, daidzein
and glycitein were 686.3, 346.6 and 45.6μg/g, respectively.

Keywords: Black soybean, Chungkukjang, Antimutagenicity, Isoflavones