Which excretory product is present in the fine skin of onions?

The excretory product present in the fine skin of onions is primarily quercetin, a type of flavonoid. Quercetin is known for its antioxidant properties and contributes to the onion's overall health benefits. Additionally, the skin of onions contains other compounds such as sulfur-containing compounds and various phenolics that may also play a role in the plant's defense mechanisms.