Effect of cooking on yellow onion quercetin.

Abstract

Flavonoids are bioactive secondary plant metabolites with a range of beneficial effects on human health. Consumption of a diet rich in these compounds might decrease the risk of circulatory and inflammatory diseases and certain cancers. Onions are a good source of quercetin derivatives with the major constituents quercetin-3,4'-glucoside and quercetin-4'-glucoside, which are not deglucosylated during cooking. There is a gradient in flavonoid content from outer to inner scales in raw onion and the former remain the richest even after cooking. Over 50% of flavonoids and soluble plant material are readily transferred from onion into soup during cooking. Cooking may increase the total amount of flavonoids available by disrupting the plant tissue and rendering better accessible.