What is an oil's smoke point?
The smoke points of an oil (or butter) is precisely what it sounds like: the temperature at which it begins to release clouds of smoke. At that point, the oil is breaking down and has a very narrow window of time left until it burns and should be tossed out.
The smoke point is different for different kinds of oils. Vegetable oils are tougher and can reach a higher temperature before smoking, making tehm good for frying. (The commonly accepted temperature for frying is somewhere between 365F-375F.) Butter burns easily, and olive oil has a pretty low smoke point, so they’re better for sautéing at relatively lower heats.
Here are a few examples of oils and their smoke points (get your thermometers ready!):
Sunflower Oil -- 440F
Canola Oil -- 400F
Butter -- 350F
Extra Virgin Olive Oil -- 320F