Sunday, August 11, 2013
Pavilion (Sheraton San Diego)
In the present study, a solid state fermentation process of black soybean was developed. Three filamentous-fungi including Rhizopus oligosporus (BCRC 31996), Rhizopus oligosporus (NTU-5), and Rhizopus oryzae (BCRC 30894) were cultivated with steam-cooked intact- and dehulled black soybeans. The effect of fermentation on the changes of total phenolic and isoflavone content, antioxidant activity (i.e. 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging effect), and the activity of b-glucosidase were evaluated. It was found that fermentation enhanced the total phenolic and isoflavone aglycone content as well as antioxidant activity of the black soybean methanol (80 % (v/v)) extracts. Among the three candidates, R. oligosporus BCRC 31996 was chosen as the working strain and dehulled Tainan NO.3 black soybeans were used as the substrate based on the relatively high total phenolic content, isoflavone aglycone accumulation, and DPPH radical scavenging effect of the fermented extracts. In a 6-day fermentation, extracts of the fermented dehulled black soybeans yielded higher total phenolic content (2876.2 μg/g) which was 1.16 times of the result from the intact soybean extracts. The DPPH scavenging effect of the fermented dehulled black soybean extract reached its maximum on the 3rd day (49.2 %). The activity of β-glucosidase of dehulled black soybean samples increased with time and resulted in the accumulation of isoflavone aglycones, which are 502.2 and 678.5 mg/g, respectively. The product of solid state black soybean fermentation may be used as a functional ingredient in the products of nutritional supplements and health foods.