When we make body care formulations, we choose specific oils and butters based on our final goals: consistency, absorption rate, skin type, etc. The same is true for cooking. Fats, like those in culinary oils, are integral to our dishes, not just to keep food from sticking to a pan, but also to affect the final flavor, consistency, texture, and more. Every cooking oil has a unique chemical composition that makes it better at some things than others. This is why one oil might be amazing in a salad dressing or for a lightly sautéed protein, but is a poor choice for grilling or deep-frying. To achieve your cooking goals, it’s important to understand culinary oils and fats. And an important element of that understanding is the smoke point.
Culinary oils are pressed and extracted from a variety of plant sources, including seeds, nuts, and fruits, which means they bring widely different flavors and health benefits to your dishes. Some are packed with flavor (think sesame oil) and others are much more neutral in flavor (sunflower or grapeseed oil). They come in refined as well as unrefined varieties, which may be advertised as raw, virgin, or cold-pressed.
As a child of the ‘70s, I grew up in a time and place when my local grocery stores only sold heat-refined, chemically extracted, bleached oils. All of these, we now know, come from some of the most genetically engineered crops, including corn oil, soybean oil, and canola oil. Still today, the mass-market forms of these oils are most often extracted with chemical solvents and then undergo further treatments, including very high heat and more chemicals to remove the original solvents and to deodorize and bleach the oils. This process, as you might imagine, also strips most of the nutritional value from the oils. I am relieved to say that today we foodies and chefs have so many other oil options, including unrefined and naturally refined culinary oils.
Unrefined oils are extracted and then simply filtered to remove impurities. This means they retain much more of their nutritional value, but they aren’t as stable. Also, because they are minimally processed, these oils taste much more like the plants they come from, which can be a positive or a negative, depending on your end goal. The unrefined culinary oil options in mainstream grocery stores have skyrocketed in my lifetime. It began with olive oil with its deep flavor and cold-pressed, extra-virgin options but, increasingly, we can find cold-pressed oils readily available that used to only be available in “health food” stores: avocado, grapeseed, sesame, hemp seed, flaxseed, pumpkin seed, walnut, coconut, etc.
Many of the highest quality refined culinary oils are now pressed and refined without using chemical solvents. Those that are expressed from soft fruit or nuts (olive, avocado, walnut, etc.) are expeller pressed and then put into a centrifuge to separate the oils from the waters. Sometimes you’ll see these labeled “cold-pressed.”
Harder oilseeds (soybean oil is a good example) often need to be steamed before pressing to achieve a good extraction, so there is some heat in that process. These naturally refined oils are also more filtered and strained than unrefined options and this process does reduce the nutrients, although not to the level of the chemically and/or heat extracted oils. It’s also important to note that this refinement process is often key to success in culinary endeavors as well as body care formulations because it gives the chef or herbalist a stable oil with a neutral smell and flavor, and these oils are also significantly more shelf-stable for storage. Often, however, these oils are not ideal for more delicate applications like salad dressings, sauces, and flavored oils for drizzling.
The smoke point of an oil is when it reaches its burning point, when it stops shimmering and starts smoking. The smoke point varies greatly among oils, ranging from less than 250°F to more than 500°F. The quality of the oil, the type of heat you’re using, how much air is in the oil container, and the free fats acid (FFA) content in that oil all impact smoke point. Oils with high FFA content are more susceptible to oxidative aging, become rancid more quickly, and smoke sooner when heated. Sometimes smoking oil is inevitable, and not a big problem, like when you’re stir-frying in a very hot wok. In general, however, it means your oil is breaking down, which in turn means it is releasing chemicals that can give your food a burnt or off flavor. Overheated natural fats can also begin releasing free radicals (unstable atoms that can damage cells). Additionally, the beneficial nutrients and phytochemicals found in many unrefined oils are destroyed when oil reaches its smoking point. So it’s important to know that the smoke point of an oil is sufficient for the type of cooking you’re doing.
In general, the more refined an oil is, the higher its smoke point will be. A higher smoke point gives an oil a wide range of uses because you can use it at higher temperatures to fry, grill, deep-fry, and more. The refined oils most recommended for high-heat cooking, grilling, and deep-frying are “high oleic,” which means they are high in monounsaturated fats. Some oils, like olive oil, are naturally high in monounsaturated fat but are also high in polyunsaturated fats which makes them less stable for both super-high-heat cooking and long-term storage. Interestingly, food scientists have been working with sunflower seeds to develop an unrefined oil that is high in monounsaturated fats but low in polyunsaturated fats in hopes of creating a more shelf-stable unrefined oil that will be appropriate for a variety of uses.
The smoke point for some unrefined oils like flaxseed, wheat germ, and walnut oil is low (around 225°F) and many experts say we shouldn’t heat them at all. They are rich in polyunsaturated fats and are lovely in smoothies, drizzles, salad dressings, etc.
Unrefined oils that are higher in monounsaturated fats, like extra virgin olive, are considered medium smoke point oils, which means you can use them for most cooking on the average home stove, including sautéing and pan-frying, slow-roasting in the oven, and even stir-frying as long as you’re not cranking the heat over about 375°F.
Naturally refined oils like coconut, grapeseed, and sunflower have much higher smoke points, ranging between 400-500°F.
*For those with visual impairment, the text version of this infographic can be found at the end of the blog.
Although there is growing evidence that saturated fats are not as bad as we all used to believe, recent studies show that replacing some saturated fats with polyunsaturated fat or nutrient-dense carbohydrates (like whole grains) can be beneficial for heart health. This makes choosing a good culinary oil a smart choice because the unsaturated and monounsaturated fats in these oils come from nuts and seeds which often have beneficial fatty acids like Omega-9 and Omega-3. Extra virgin olive oil, avocado oil, and flaxseed oil are excellent examples of oils with beneficial fatty acids.
From a tastebud standpoint, the other consideration on oil choice is whether you want a flavored oil or a neutral one. If you want the flavor of a food to stand out without any accompanying flavors from oils, you may want to look for a neutral-tasting, naturally refined oil. Sometimes, of course, the flavor of an oil is integral to the dish itself. It’s those cases when I am particularly fussy about the quality of my oils because their flavor is going to directly affect the success of a dish. These tend to be unrefined oils, so they also don’t have the shelf life of a more refined oil, and storing them somewhere away from light and heat is key to keeping them tasting good.
Truthfully, there is no reason most of us need to know the nutritional values and smoke points of every oil, but it is helpful to know how to best enjoy the oils you commonly use and to learn about a few new ones that could enhance your culinary expression.
I hope that this is helpful, happy cooking!
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