Abstract
The antioxidative activity of red and white Welsh onions was evaluated by measuring the radical scavenging and ferric reducing antioxidative activities (TEAC and FRAP, respectively). Both activities of red Welsh onion were much higher than those of the white variety, the strong antioxidative activities being found in the red, and not in the white or green part of red Welsh onion. After heating for 30 or 60 min in boiling water, TEAC in the vegetable tissue of red Welsh onion was decreased to 25-30% of the level in the raw sample; about 40% of the activity had been extracted into the boiling water, the sum of these activities being 60-70% of the level in the raw sample. In the case of FRAP, about 25% was found in the vegetable tissue and about 30% in the boiling water, the sum of these activities being 50-60% of that in the raw sample. The antioxidative components in the three parts of red Welsh onion were also estimated: high amounts of quercetin and anthocyanin were found in the red part, ascorbic acid was found in the white part, and quercetin, kaempferol, and ascorbic acid were found in the green part.
