Antioxidant properties of fermented soybean broth

Soybean broth (SB) and fermented soybean broth (FSB), at 100% exhibited good antioxidant activities of 0.85 and 0.80, respectively. Only FSB exhibited an excellent reducing power of 0.76–0.86 at 5–100%. FSB showed an excellent scavenging activity on 1,1-diphenyl-2-picrylhydrazyl radicals (100%) at 20–100%, while SB only at 100%. FSB at 20–100% inhibited the production of superoxide anion radicals by 81–93% but SB showed no inhibition. As its concentrations increased from 2–100%, the scavenging effect of FSB on hydroxyl radicals increased from 30–96%, whereas that of SB increased from 5–76%. Both FSB and SB were good chelators for ferrous ions. For cupric ions, SB showed significantly higher chelating effect than did FSB. These results showed that FSB was superior to SB in most antioxidant properties and that SB and FSB, more specifically FSB, might be potential antioxidants for application in food products.