Quercetin in onion (Allium cepa L.) after heat-treatment simulating home preparation
2005
Lombard, K. | Peffley, E. | Geoffriau, E. | Thompson, L. | Herring, A.
Quercetin content in onion (Allium cepa L.), represented mainly by 3,4'-O-quercetin diglucoside (3,4'-Qdg) and 4'-O-quercetin glucoside (4'-Qmg), was examined in five cultivars before and after three cooking treatments (sauteing, baking, and boiling). Baking and sauteing produced a 7-25% gain in quercetin concentration, while boiling produced an 18% decrease in quercetin concentration. Ratios of 3,4'-Qdg to 4'-Qmg in tissues ranged from 1:1.3 and 1:1.7, and combined the two conjugates represented 89-90% of total flavonol content in treatment and raw control means indicating heat stability of the flavonols. Changes in flavonol concentrations as a result of cooking method were consistent across all five cultivars.
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