Because heat is such an integral part of cooking, yet is also one of the factors that affects the quality of an olive oil, many people assume that applying heat to olive oil in cooking applications, such as shallow and deep frying, stir-frying or sauteing, is a practice that should be avoided.
This is a myth. Heating an extra virgin olive oil to frying temperature does not hurt or substantially alter the chemical composition of the oil if kept below the smoke point, and is still very good for you due to its polyphenol content and high levels of oleic acid – a very stable compound that does not easily oxidize.
The alternatives – eg. canola, soybean and corn oils – are significantly less stable, contain little or no polyphenols, and can break down into dangerous, toxic by-products at high temperatures due to accelerated oxidation. Olive oil, coconut oil and palm oil are the most stable of all fats when heated.
The smoke point of a true extra virgin olive oil is 410°F, well above the 350-375°F that is required for most frying. If the olive oil is higher in acidity and/or contains impurities (often representative of lower grade, mass produced oils), the smoke point can be reduced by up to 50°F. That’s why we recommend that you fry foods with a high-quality olive oil, and avoid mixing it with other types of oils.
To properly fry with extra virgin olive oil without destabilization, first heat the oil in a heavy pot or pan to the suggested temperature by using an oil thermometer (sometimes called deep fry thermometer). Starting at the burner’s medium setting will allow you to raise it little-by-little until you achieve the right temperature. Adding the food to the pot or pan after the oil is fully heated will prevent the food from absorbing too much oil and becoming soggy.
Deep Frying tip: Though the added flavor will be best when frying the first time, reusing a large pot of olive oil 4-5 times is still safe and flavorful (and not to mention cost-effective) if doing so within a short timeframe and if properly strained after each use.
Frying with olive oil has been a standard practice in the Mediterranean diet for centuries. Try shallow frying eggs, sliced potatoes or fish in extra virgin olive oil and you will be amazed by the results.