Phenolic compound (polyphenol) belonging to the large group of flavonoids (plant pigments) as a glycoside bound to sugar. The yellow pigment, also known as quercitin or quercetin, is found particularly in the bark of the American larch (Quercus tinctoria), as well as in apples, broccoli and onions. It is the most common flavonoid colouring agent in grapes. The red wine varieties Cabernet Franc, Cabernet Sauvignon, Nebbiolo and Pinot Noir are particularly rich in quercetin. The substance is formed particularly in intense sunlight. Quercetin also passes from the wood into the wine during barrel ageing. The substance has an antioxidant effect and also has a positive, health-promoting effect as a radical scavenger. However, higher levels of quercetin in wine can also lead to headaches.
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