Characterization of fermented black soybean natto inoculated with Bacillus natto during fermentation.
BACKGROUND
To make nutrients more accessible and further increase biological activity, cooked black soybeans were inoculated with Bacillus natto and fermented at 37 degrees C for 48 h. The changes in physiochemical properties of fermented black soybean natto were investigated.


RESULTS
The inoculation procedure significantly increased moisture, viscosity, color, polyphenol compounds and anthocyanin, and significantly decreased hardness after 48 h fermentation. Fibrinolytic and caseinolytic protease, beta-glucosidase activities, TCA-soluble nitrogen, and ammonia nitrogen contents in the inoculated samples significantly increased as fermentation time increased. Genistin and daidzin concentrations gradually decreased with increased fermentation time. However, genistein and daidzein increased with fermentation time, which reached 316.8 and 305.2 microg g(-1) during 48 h fermentation, respectively. DPPH radical scavenging activities of the fermented black soybeans increased linearly with fermentation time and concentration. Compared with the soaked black soybeans and cooked black soybeans, the fermented black soybeans with B. natto resulted in higher scavenging activity towards DPPH radicals, which correlated well with the content of total phenols (r = 0.9254, P < 0.05) and aglycone isoflavone (r = 0.9861, P < 0.05).


CONCLUSIONS
Black soybean natto fermented by B. natto has the potential to become a functional food because of its high antioxidant activity.
Hu
Yongjin
Y
School of Food Science and Technology, Yunnan Agricultural University, Kunming 650201, Yunnan, China. huyjinsytu@yahoo.com.cn
Ge
Changrong
C
Yuan
Wei
W
Zhu
Renjun
R
Zhang
Wujiu
W
Du
Lijuan
L
Xue
Jie
J
D000975:Antioxidants / Q000494:pharmacology*; D001407:Bacillus / Q000378:metabolism*; D003116:Color; D005285:Fermentation; D055951:Functional Food; D007529:Isoflavones / Q000032:analysis; D028321:Plant Preparations / Q000494:pharmacology*; D012639:Seeds / Q000737:chemistry / Q000378:metabolism / Q000382:microbiology; D045730:Soy Foods / Q000032:analysis* / Q000382:microbiology; D013025:Glycine max / Q000737:chemistry / Q000378:metabolism / Q000382:microbiology
D000975:Antioxidants; D007529:Isoflavones; D028321:Plant Preparations