Published Monday, Sep. 28, 2015
What does “smoke point” mean? I was told not to cook with extra virgin olive oil because it has a low smoke point and will break down when it’s heated. Is this true? What is the best oil to sauté vegetables with?
It’s a myth that you can’t cook over high heat using olive oil. Contrary to popular belief, you can even sauté vegetables with extra virgin olive oil.
Smoke point refers to the temperature at which an oil starts to burn and smoke. When you cook with oil that’s been heated past its smoke point, you do more than impart a burnt flavour to foods. Beneficial nutrients and phytochemicals found in many unrefined oils are destroyed when the oil is overheated. Overheating also creates harmful free radicals.
The smoke point of cooking oils varies widely. In general, the more refined an oil, the higher its smoke point, because refining removes impurities and free fatty acids that can cause the oil to smoke.
Refined oils typically have a neutral taste and odour and a clear appearance. Light olive oil (light in colour, not in calories), for example, has been refined and has a higher smoke point (486 degrees Fahrenheit) than extra virgin olive oil (410 degrees F), which has not been refined.
Even so, the smoke point of extra virgin olive oil makes it suitable for many types of cooking. Cooking on average home stoves, such as roasting in the oven and sautéeing, pan-frying and stir-frying over medium-high heat, is typically done between 250 and 400 degrees Fahrenheit.
Other oils that have high smoke points (400 degrees F and higher) include avocado oil (refined), almond oil, corn oil, canola oil, grapeseed oil, peanut oil, safflower oil, sesame oil and sunflower oil. These oils are better suited for cooking at higher temperatures.
Unrefined oils such as flaxseed oil, wheat germ oil and walnut oil have a low smoke point and should not be heated.
Whether you use cooking oil for stir-frying, drizzling over vegetables or blending in a smoothie, don’t stock up on Costco-sized bottles you won’t use within a year. Over time, heat and light can generate free radicals that degrade an oil’s taste and quality. Store cooking oils in a cool, dark cupboard or the refrigerator.
A guide to cooking with oils
The cooking oil you choose depends on how you intend to use it, its nutritional qualities and its flavour. Depending on the source referenced, the smoke point of cooking oils will vary slightly due to impurities in the oil and the fact that oils break down gradually, rather than at one specific temperature.
Expeller-pressed versus cold-pressed oils
Oils are extracted from nuts, seeds, olives, grains or legumes by chemical (e.g., food-grade hexane) or mechanical processes.
Expeller pressing is a chemical-free process that removes the oils from their source using a mechanical press. Minimal heat is generated in the process.
Cold-pressed oils are extracted using an expeller press but under a carefully controlled temperature setting below 120 degrees Fahrenheit. Cooler temperatures preserve the flavour and aroma of heat-sensitive oils. Cold pressing also retains naturally occurring phytochemicals, such as polyphenols and plant sterols, as well as vitamin E.
Leslie Beck, a registered dietitian, is based at the Medisys clinic in Toronto.