Garlic – Perhaps the most widely used spice in the world, the bulbs of Allium sativum have been cultivated in central Asia and the Middle East for thousands of years. It was originally used in medical and magical potions, but the ancient Egyptians discovered its benefits in the kitchen and began growing it on a large scale. It is available in many forms, including fresh heads of garlic, dried garlic flakes and powder, garlic salt, extract, and juice. While some of these products may offer something in terms of convenience, they all lack the flavour of true, fresh garlic, and should only be used when fresh garlic is unavailable.
In addition to Allium sativum (which we consider to be basic, regular old garlic), several other related species are also used around the world. The most familiar to Americans is probably the bulb of A. ampeloprasum, which is actually a type of leek and is marketed as “elephant garlic.” The cloves of this plant may weigh up to an ounce (28 g) each, and although they are too mild to replace true garlic in cooking, the whole cloves are good roasted with other vegetables. Similarly, wild members of the genus are often collected and used as garlic. In southern Europe rocambole (A. sativum var. ophioscorodon) and ramsons (A. ursinum) are often cultivated and sold in markets, while aficionados of wild American garlic (A. canadense) and wild onions (or ramps, A. tricoccum) will most likely have to collect their own.
The characteristic odour of garlic (as with the other members of the onion family) is formed when enzymes and other compounds come into contact with each other as a result of the crushing, slicing, or chopping of the garlic, and this chemical activity results in the production of several disulphate compounds which owe their pungency to the sulphur compounds they contain. In other words, the more finely garlic is chopped, the more pungent it becomes. This accounts for why some recipes would have you mash the garlic to a pulp (as in aioli and pesto Genovese) for the maximum garlic flavour, and others require a more restrained chopping, slicing, and even leaving the garlic cloves whole in order to moderate the flavour. When garlic is heated the disulphate molecules are rearranged to form different, less pungent disulphates, which is why garlic and its cousins lose so much of their punch when cooked.