https://www.sciencedirect.com/science/article/pii/B9780123813732001320
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Flavonols are the most ubiquitous flavonoids in foods, the main representatives being quercetin, kaempferol, and myricetin.
They are present mainly in onions at concentrations up to 1.2 g kg fresh weight, but also in kale, leeks, broccoli, etc. They can also be found in red wine and tea in their glycosylated form with glucose or rhamnose.
Fruit often contains between 5 and 10 different flavonol glycosides, which accumulate in the outer and aerial part (leaves and skin). Big differences in concentration can be found in different fruits, even coming from the same tree, since their biosynthesis is favored by sunlight exposure.
Similar behavior is found in leafy vegetables, in which the concentration is also higher in the green outer leaves compared with the less colored inner ones. Flavonols can also be found in beverages such as apple and cranberry juices and tea.
