Smoke Point

• The boiling points and smoke points of cooking oils differ. For this reason, certain oils are preferred for cooking at higher temperatures, while others are considered more suitable for cooking at lower temperatures.

Temperature

• The temperature at which an oil will reach its smoke point is influenced by the purity of the oil. Safflower oil has the highest smoke point at 510° F, while olive oil at the other end of the scale, reaches its smoke point at 375° F. The boiling point of soybean oil, which is a cheap and common cooking oil, is approximately 572° F. Compare this to the smoke point of soybean oil, which is 495° F.

Chemistry

• Oils boil at different temperatures because the chemical bonds that hold them together are of varying strengths. A boiling point will be higher because it takes more energy to break those bonds. When an oil reaches its smoke point, it emits an acrid smell and the air will fill with smoke. It's believed that oil that has gone past its smoke point contains unhealthy free radicals.