Anyone can toss some oil into a pan and cook, but if you want to up your cooking game, consider using different oils based on the dish you're making and how you plan to cook it. Using the right one can mean the difference between a tasty, well-cooked meal and a smoke alarm going off over your burned food.
We're not suggesting that you run out and buy a dozen different oils just in case you need them, but there is some benefit to having more than one type of cooking oil in your kitchen. Depending on whether you plan to bake, fry, broil, or grill, a different oil will yield different results in your food, and give you more control over the cooking time and temperature.
Smoke Point: The Number That Determines When Oil Goes from Tasty to Terrible
First, a little science. Each different type of oil or fat has its own smoke point, or the temperature at which it begins to break down, smoke, and start to taste awful. Around that same temperature, the flavor and nutritional value falls off as well. What you're left with isn't very tasty and isn't very good for you.
The chemical process behind this is simple: As you heat a fat of any kind, it begins to break down into free fatty acids and glycerol. As the temperature rises, the glycerol breaks down further and produces a bitter-smelling, acrid chemical called acrolein. It's that acrolein in the smoke that makes your eyes itch, and it's also what makes the food you cook in that overheated oil taste terrible. Acrolein is no good for you either—too much is toxic, and it irritates the eyes, nose, throat, and ears when its airborne.
This is why it's important to choose the right type of oil for the cooking method and the dish you're going to make. If you plan to fry or grill, you want an oil that will stand up to high heat without breaking down on you. If you're going to use the oven, you have some more flexibility depending on whether you plan to bake, broil, and the temperature you set. With the right oil and the right cooking method, you'll taste a noticeable difference in your food.
Use Flaxseed Oil, Olive Oil, and Butter for Low-Temperature Cooking and Baking
As a rule, unrefined oils, dairy products, and animal fats have the lowest smoke points, and are best suited for lower-temperature cooking like baking, simmering, and low-heat pan frying. While unrefined oils are as close to the natural flavor of the oil you can get, that they have all of the free fatty acids and other ingredients that lower the oil's smoke point. This rule extends to full-fat diary products, which have milk solids and other fats in them that break down and burn easily. Here are a few oils in this range best reserved for lower-heat preparation methods, where you actually want to taste the oil or fat you're using:
Flaxseed Oil: Smokes at approx 225°F/107°C
Unrefined Walnut Oil: Smokes at approx 320°F/160°C
Unrefined Olive Oil: Smokes at approx 320-325°F/160-162°C
Butter or Lard: Smokes at approx 350-375°F/176-190°C
It's important to note that as you refine these oils, clarify them, or buy higher quality versions that are free of the same impurities or extra fatty acids (that some people would say clarify the flavor and others complain removes it from its natural quality) the smoke point increases. For example, clarified butter, or Ghee, smokes at a whopping 485°F (252°C), making it ideal for high-heat cooking like stir frying and grilling. Photo by Nicholas Humfrey.
Use Coconut Oil, Canola Oil, and Extra Virgin Olive Oil for Medium-Heat Cooking and Frying
Most of your middle of the road oils have applications in low-heat and cold preparations but can also be used on the stove or in the oven. Refined oils—the kind you'll find in most grocery stores—make their way up here, along with some all-purpose oils that you may already have. For example:
Coconut Oil: Smokes at approx 350°F/176°C
Extra Virgin, High-Quality Olive Oil: Smokes at approx 375-400°F/190-204°C
Refined Canola Oil: Smokes at approx 400°F/204°C
Corn Oil: Smokes at 400-450°F/204-232°C
Other refined oils, like Cottonseed oil (420°F/216°C) and Grapeseed Oil (420°F/216°C) are on the leading edge of this category. In general, these are the oils that are the most flexible, which is why they're easily available almost everywhere. Photo by Steven Tom.
Since the level of refinement and the quality of an oil has a huge effect on its smoke point and final flavor, we should note that there's some controversy around the quality of olive oil, especially imported olive oils that are often mixed with oils from different places with different ages, and then labeled "extra virgin" and sold at a premium. Before you buy, check for a harvest date and weed out the fakes. Check out the full UC Davis study (PDF) that blew the lid off of the issue and the brands they tested for more information.
Use Peanut Oil, Avocado Oil, and Ghee for High-Heat Grilling and Deep Frying
The highest-smoke point oils are generally reserved for high-heat frying, brushing on the grill, and deep frying. Some of these are best used because of their high smoke point and their flavor, others are so heavily refined that a high smoke point is pretty much all they have going for them. A few examples:
Sesame Oil: Smokes at approx 410°F/210°C
Peanut Oil: Smokes at approx 400-450°F/204-232°C
Palm Oil: Smokes at approx 450°F/232°C
Ghee (Clarified Butter): Smokes at approx 485°F/252°C
Refined Soybean Oil: Smokes at approx 495°F/257°C
Avocado Oil: Smokes at approx 520°F/271°C
Depending on your opinion of highly saturated oils, some of these may be your go-to oils or they may be your never-use oils. Regardless, the fact is they're able to withstand the most heat, and often used in situations where extremely high temperatures are required, like broiling, deep frying, stir frying, or other situations where direct contact with flame are required. Keep in mind that some of them—notably peanut oil and avocado oil—impart their own flavors to your dish, so only use them when the taste is complimentary. Photo by Jack Liddon.
Finally, a note about soybean oil—soybean oil's smoke point varies widely based on its level of refinement. Unrefined soy oil can smoke as low as 320°F/160°C and refined soy oil at 350°F/176°C. Almost pure soy bean oil is what's listed here, so remember that when you go shopping if soy oil is a staple in your home.
Choose Your Favorites, and Keep Them On Hand
Like we said earlier, there's no reason to keep a half-dozen oils in your pantry (besides, you don't want your oil to go rancid on you.) Pick a few that you really enjoy using, both for flavor and for temperature. This cooking oil comparison chart, made with the help of Lifehacker friend, nutritionist, and Registered Dietitian Andy Belatti, does a great job of showing you which oils are best left for salads and low-heat preparations versus the ones that can stand a little heat.
I keep soybean oil, extra virgin olive oil, and sesame oil in my kitchen. The soy oil has the highest smoke point, so it's great for grilling or high-heat frying. The olive oil is tasty, and best for baking and low-and-slow sauteeing (and cold preparations, like salad dressing.) The sesame oil can stand high heat, so I use it for stir frying, but I don't shy away from using it to add flavor in colder preparations. I've been experimenting with coconut oil too.
Finally, keep your budget in mind. Some highly refined oils and others that are more natural (or have dubious health benefits) are pretty expensive, so do your homework before buying. There's nothing worse than buying an oil just because it has a high smoke point or someone's book says it's the cure for your ills only to find out it tastes terrible in everything. For a more complete guide to various oil types and their smoke points, check out this table at the Good Eats fan page (nicely formatted for copy/pasting), this chart from Cooking for Engineers, or Wikipedia's list of common oils and smoke points.