Understanding cooking oil smoke points
Everything you know about smoke points is wrong. Smoke Points are more than just a simple number. Read on to learn why.
Definition of the smoke point of cooking oil
The smoke point of an oil is the temperature at which the oil begins to smoke. This is not to be confused with a flash point, which is the temperature at which oil vapors will ignite.
Measure the smoke point of cooking oil
The American Oil Chemists' Society recommends the Cleveland Open Cup method (9a-48 method) for measuring the smoke point. The oil is heated and when light blue smoke is observed the temperature is recorded as the smoke point. The problem with this and any method of measuring smoke point is subjectivity. It is up to the analyst to determine when oil is emitting smoke.
In addition, oil smoke points vary widely from sample to sample. An oil's smoke point temperature can vary by ±70°F depending on the age of the oil, field conditions, time of year, grade, level of refinement/filtration, fatty acid composition, etc. To report smoke points correctly, multiple samples of the oil should be measured and the smoke point should be reported as a range.
The smoke point diagrams available on the internet and published in books are generally based on a single sample. The number you see online is the smoke point of the oil that the analyst measured and may not be the smoke point of the oil you have in your kitchen. For this reason, official smoke point tables are often accompanied by a disclaimer like this one.
"The values in this table represent typical smoke, flash, To, and burn points for commercially available edible fats and oils. The values are based on a single test for each fat and oil source, therefore they do not represent or reflect the statistically valid average A range of values attributable to each of the base oils. Smoke, flash, and fire points may vary within a base oil due to factors such as processing techniques and/or seasonal variations. In addition, there may be analyst subjectivity in the use of this test method (i.e. AOCS Cc 9a-48 method, Cleveland Open Cup)."
The surface also influences the smoke point of the oil. A wide, shallow pan with a thin layer of oil will have a different smoke point than a deep pot. In practice, the laboratory smoke point of an oil is not a good indicator of when the oil will smoke when cooking at home.
Smoke points should be considered as general, not precise values. Professor Robert Wolke explains this topic in detail in his book What Einstein Told His Cook: Kitchen Science Explained. Here are the smoke point ranges for olive oil and other common cooking oils.
COOKING OIL/FAT SMOKE POINT °F
Olive Oil or Extra Light Olive Oil 390 - 468°F
Sunflower oil 440 - 450°F
Soybean Oil 440-450°F
Canola Oil 435 - 445°F
Peanut Oil 420 - 430°F
Corn Oil 400-415°F
Extra Virgin Olive Oil 350 - 410°F
Shortening 360°F
Virgin Coconut Oil 350°F
Keep in mind that the average stovetop cooking is 350⁰F. As you can see, olive oil's smoke point is similar to or higher than the smoke point of most cooking oils and high enough for all types of cooking.
The smoke point is not a reliable indicator of cooking oil stability
As a final note, researchers have found that smoke point does not correlate with how quickly an oil breaks down when heated. Extra virgin olive oil is more stable than cooking oils with a higher smoke point.