Fermentation with Bacillus spp. as a bioprocess to enhance anthocyanin content, the angiotensin converting enzyme inhibitory effect, and the reducing activity of black soybeans.

Food possessing anthocyanins, angiotensin converting enzyme (ACE) inhibitory activity or reducing activity show beneficial effect on human health. To develop healthy food, black soybeans were fermented with either Bacillus subtilis BCRC 14715 or Bacillus sp. CN11, or a mixture of both Bacillus spp. in the present study. The anthocyanin content, the ACE inhibitory activity and the reducing power of the fermented black soybean were then examined. It was found that the ACE inhibitory activity of the extracts of bean and viscous material from the fermented black soybeans varied with extraction solvents and starter organism, yet increased as the fermentation period was extended, regardless of starter organism. After 18 h of fermentation, the water extract of bean showed less ACE inhibitory activity than did the respective 80% ethanol extract. While the water extract of viscous material showed a higher ACE inhibitory activity than the respective ethanol extract. With respect to extraction yield, it was found that the ACE inhibitor in the fermented black soybean could be extracted more efficiently with water than 80% ethanol. Fermentation with B. subtilis BCRC 14715 was also found to increase the anthocyanin content of black soybean and the reducing activity of the extracts. Finally, the 80% ethanol extract showed a higher reducing activity than the water extract.

Enhancement of antioxidant activity, total phenolic and flavonoid content of black soybeans by solid state fermentation with Bacillus subtilis BCRC 14715.

In the present study, a solid state fermentation of black soybeans with Bacillus subtilis BCRC 14715 was performed. The effect of fermentation on the changes of total phenolic and flavonoid content and antioxidant activities including 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging effect, and Fe(2+)-chelating ability exerted by various solvent (water, 80% methanol, 80% ethanol, 80% acetone) extracts of black soybeans was examined. It was found that fermentation enhanced the total phenolic and flavonoid content as well as antioxidant activity of the black soybean extract. Among the various extracts examined, the acetone extract of fermented black soybeans showed the highest total phenolic and flavonoid content. The acetone extract and the methanol extract of fermented black soybeans showed the highest DPPH free radical-scavenging effect and Fe(2+)-chelating ability, respectively. Analysis of extraction yields showed that the active principle associated with the DPPH radical-scavenging effect was most efficiently extracted from black soybeans using water, regardless of fermentation. Water and methanol effectively extract the Fe(2+)-chelating principles from non-fermented and fermented black soybeans, respectively.