The Flavors and Sting of Raw Alliums

The distinctive flavors of the onion family come from its defensive use of the element sulfur. The growing plants take up sulfur from the soil and incorporate it into four different kinds of chemical ammunition, which float in the cell fluids while their enzyme trigger is held separately in a storage vacuole. When the cell is damaged by chopping or chewing, the enzyme escapes and breaks the ammunition molecules in half to produce irritating, strong-smelling sulfurous molecules. Some of these are very reactive and unstable, so they continue to evolve into other compounds. The mixture of molecules produced creates the food’s raw flavor, and depends on the initial ammunition, how thoroughly the tissue is damaged, how much oxygen gets into the reactions, and how long the reactions go on. Onion flavor typically includes apple-like, burning, rubbery, and bitter notes; leek flavor has cabbage-like, creamy, and meaty aspects, while garlic seems especially potent because it produces a hundredfold higher concentration of initial reaction products than do other alliums. Chopping, pounding in a mortar, and pureeing in a food processor all give distinctive results. Chopped alliums to be eaten raw—as a garnish or in an uncooked sauce—are best rinsed to remove all the sulfur compounds from the damaged surfaces, since these tend to become harsher with time and exposure to the air.