The Smoke Point

Most fats begin to decompose at temperatures well below their boiling points, and may even spontaneously ignite on the stovetop if their fumes come into contact with the gas flame. These facts limit the maximum useful temperature of cooking fats. The characteristic temperature at which a fat breaks down into visible gaseous products is called the smoke point. Not only are the smoky fumes obnoxious, but the other materials that remain in the liquid, including chemically active free fatty acids, tend to ruin the flavor of the food being cooked.