Many of the less attractive odors in some vegetables are due to sulfur compounds . Cabbage, Brussels sprouts, and cauliflower owe their flower to sulfur compounds called isothiocioanates. In raw vegetables, these compounds are bound to sugar and become odorless. But when plant tissues are damaged by cutting, or biting, the sugar-containing complexes are released. When cabbage is cooked in boiling water, new sulfur compounds with a strong odor are produced, including hydrogen sulfide.
Garlic , onion , leek, and chives also owe their smells and flavors to sulfur compounds. Boiled broccoli and cauliflower also contain sulfur compounds that give it its characteristic "stink."
