Both liquid and solid fats have the remarkable property of separating out their own flavor molecules and embedding them in what surrounds them. In soups and stews, fat can be added during cooking and later removed; its flavor remains. Other flavors, as from garlic or onions in sautéing, are easily absorbed by fats so that during cooking they are efficiently diffused. Because they are more slowly digested than other nutrients, fats give us a sustained feeling of satiety. Fats are derived from animal sources (butter, lard, and shortening) and vegetable sources (grain, seed, and nut oils). As a general rule, most fats that are solid when refrigerated and at room temperature come from animal sources; those that are liquid at room temperature are vegetable oils. Of primary concern in choosing fats for cooking is whether they are saturated, monounsaturated, or polyunsaturated. Saturated fats play a major role in raising blood cholesterol levels and should be eaten in moderation. These fats are derived mainly from animal products, although certain vegetable oils (coconut and palm) are also highly saturated. Animal fats also contain cholesterol, while those derived from vegetable sources do not. It was long believed that polyunsaturated fats, such as corn, soybean, and sunflower oils, were the most healthful, but now the consensus is that primarily monounsaturated oils, like olive and canola, are preferable because they may be capable of lowering blood cholesterol levels.
Also important in choosing which fats to use in cooking is the taste and texture they impart to foods. Nothing reveals the personality of a cuisine so much as the fat on which it is based. Olive oil evokes sunny Mediterranean cuisine, bacon arouses memories of the American South, and sweet butter brings forth memories of fine French dishes and well-browned homemade cakes and cookies. Not only flavors but food textures change with the use of different fats, whose characteristics are as individual as their tastes.
