The Flavors of Cooked Alliums

When onions and their relatives are heated, the various sulfur compounds react with each other and with other substances to produce a range of characteristic flavor molecules. The cooking method, temperature, and medium strongly affect the flavor balance. Baking, drying, and microwaving tend to generate trisulfides, the characteristic notes of overcooked cabbage. Cooking at high temperatures in fat produces more volatiles and a stronger flavor than do other techniques. Relatively mild garlic compounds persist in butter but are changed to rubbery, pungent notes in more reactive unsaturated vegetable oils. Blanching whole garlic apparently inactivates the flavor-generating enzyme and limits its action, so the flavor of garlic cooked whole is only slightly pungent, and sweet, nutty notes come to the fore. Similarly, pickled garlic and onions are relatively mild.