Antioxidant activity of onion and its effect by fermented treatment

DPPH (2, 2-diphenyl-1-picrylhydrazyl hydrate) radical-scavenging activity, linoleic acid oxidation inhibitory and reducing power of water extracts of onion were determined to evaluate the antioxidant activity of onions(white onion,red onion and yellow onion). Red onion was fermented with salt and sugar, the change of DPPH radical-scavenging activity was detected. The results indicated that the order of antioxidant activity of onions was red onionyellow onionwhite onion, and fermentation can increase the antioxidant activity of red onion.