2004 Volume 10 Issue 3 Pages 324-327
Water extracts and 50% ethanol extracts of 14 samples of sufu (fermented tofu) produced in various regions of China were prepared, and their DPPH (α,α-Diphenyl-β-pricryl-hydrazyl) radical-scavenging activity and isoflavone content were determined. Although the extracts showed different radical-scavenging activity levels depending on their color and region of production, all contained highly active components. Radical-scavenging activity in the water extracts ranged from 2.03 to 11.93 μg α-tocopherol/mg, while that for the 50% ethanol extracts ranged from 2.14 to 14.62 μg α-tocopherol/mg. Radical-scavenging activity in extracts from grey sufu was higher than that found in red or white sufu. Samples from the same regions showed similar radical-scavenging activity, but there was no clear directional tendency (north/south, east/west) for the produced sufu to have high activity. Most of the isoflavone in sufu was shown to be in the form of aglycone. Isoflavone aglycones in water extracts ranged from 50.2 to 179.3 μg/g of dry matter, and that in 50% ethanol extracts ranged from 199.0 to 706.9 μg/g of dry matter.