Cooking Oils, from Fields to Frying Pans

Cooking Oils, from Fields to Frying Pans
Fried foods are an everyday part of the diet here in the South. You’ll find them on your plate at the local diner, as french fries, hash browns, onion rings, fried okra, fried catfish, fried chicken, and Mama Gertie’s famous tater tots.  We southerners even came up with deep-fried turkey to get our fix during Thanksgiving. Sadly, we also have the highest stroke and heart disease rate in the country, which begs the question: Are the oils we’re using making us sick? Of course they are. While you may long ago have eschewed “fried foods,” you’ll want to read this article if you ever eat potato chips, tortilla chips, popcorn, fried eggs, stir-fry vegetables, or any food cooked at temperatures above 350 F.

Oils are a relatively recent addition to the human diet for the fact that creating them is cumbersome. It requires either a device that forces the crushed seeds against a metal head (a process called expeller-pressing) or chemical solvents, such as hexane, to extract oil from the nut, seed, or fruit being used.  The solvent method is more popular because it is less expensive and easier; it pulls almost 100% of the oil from the seed (compared to 50%-70% for expeller-pressing). One problem is that hexane is harmful to the environment, and while there are no detectable hexane residues in the extracted oil (they evaporate), many consumers would rather choose those that are expeller-pressed (see Choosing Healthy Oils).

Both methods produce oil that can be sold to natural food stores as unrefined. The majority of these, though, go on to be processed to a greater degree to generate refined oils that have a longer shelf-life and a higher smoke point (the temperature which causes the oil to degrade). These oils, labeled as refined oils, can be found at both natural food stores and mainstream supermarkets. So, before we go any further, let’s consider what constitutes healthy oil.

Choosing Healthy Oils

The questions to ask are:

1)   How was this oil produced?

Expeller-pressed oils (sold as unrefined or refined) are healthier than solvent-extracted oils. Unrefined expeller-pressed oils retain more nutrients (including antioxidants) that are used by your body to metabolize fats more efficiently. I recommend that you choose organic, expeller-pressed, unrefined oils whenever possible. Organic oils are from plants grown without the use of synthetic pesticides, fungicides, fertilizers, or herbicides. Spectrum Naturals is one company that makes a wide-variety of quality products, including mayonnaise, made with expeller-pressed oils.

2)   How old is the oil?

To minimize the amount of rancid or damaged oils that you consume, buy oil in smaller containers, keep it out of the light, and consume it within three months. Look on the package for the date when the oil was produced. You may wish to refrigerate your oils to prolong their shelf life, although olive oil solidifies at cooler temperatures and should be stored in a dark pantry. 

3)   Nutritionally, what are the considerations?

Unrefined oils have more nutritional value than refined oils. Beyond that, consider the main types of fat the oil contains. In the 1960s, saturated fats (butter, beef, cheese, ice cream, coconut oil) were identified as unhealthy for the heart and Americans were told to switch to margarine and vegetable oil. It was a poor recommendation. Today, Americans that struggle with high cholesterol levels are told to lower saturated fats and avoid hard-stick margarine (trans fat). A better recommendation is to choose quality saturated fats, eat them in moderation, AND add more plant foods to the diet.

Saturated (butter, lard, coconut oil, palm oil)
Cultures that eat a diet rich in plant foods, and are moderate with saturated fats, have far lower disease rates than Americans. The French paradox (low heart disease despite regular use of butter and cream sauces) may be explained in part by the inclusion of more protective plant foods, including red wine. Consider that many island populations eat a diet rich in coconut milk and coconut oil/palm oil and have lower heart disease rates than Westerners. One plausible explanation is that coconuts are the only significant source of saturated fats in their diet (the traditional island diet is rich in fruits, vegetables, and fish). Keep in mind, too, that much of the past research implicating coconut oil used refined, and often hydrogenated, coconut oil.

Our recent ancestors used butter regularly but also ate far more beans and vegetables and less red meat, cheese, and ice cream. Choose high quality saturated fats, such as organic butter and virgin (also called extra-virgin) coconut oil and use these in small amounts. 

Polyunsaturated (vegetable oil, soybean, sunflower, safflower, flaxseed oil, grapeseed oil, sesame oil)
The regular consumption of polyunsaturated oils drives up our intake of omega-6 fats. Researchers believe that this is a problem and that too many omega-6 fats relative to omega-3 fats increase inflammation and disease rates. For this reason, it is wise to improve this ratio by increasing omega-3 fats, reducing omega-6 fats, or both. The easiest way to reduce omega-6 fats is to replace polyunsaturated oils with monounsaturated oils (the primary fat being an omega-9 fat called oleic acid).

Natural food manufacturers regularly use high-oleic sunflower or high-oleic safflower oil (from a plant variety that was hybridized using traditional methods) to replace some of the omega-6 fats with oleic acid. When buying potato or tortilla chips, look for those that were fried with high-oleic oil instead of regular polyunsaturated oils. Two good polyunsaturated oils to consider when cooking are grapeseed oil and sesame oil (see below).

Monounsaturated (olive oil, almond oil, avocado oil, canola oil)
There is good evidence that extra-virgin olive oil contains numerous compounds that may help prevent disease. Populations that regularly consume olive oil have lower rates of heart disease and cancer.

Extra-virgin olive is the healthiest type of oil to use on a daily basis. The term “extra-virgin” indicates that the oil was derived from the first pressing of the olive. Light olive oil is more refined but as you’ll see in the next section, can be a good choice when cooking foods at higher temperatures. 

Canola oil is also rich in monounsaturated fats. While there are many negative claims made about canola, there is little evidence to substantiate them. What canola lacks is a long history of use. It was developed in Canada in the 1970s through traditional plant breeding methods to remove a toxic fatty acid called euricic acid. Commercial canola sold in markets today does not contain euricic acid. A large percentage of canola oil available, however, has been genetically modified (GMO) and has been sprayed with pesticides. Spectrum Naturals makes several organic (non-GMO), expeller-pressed canola oil products that are available in natural foods markets.

4)   Am I using this oil appropriately?

Most people know that they shouldn’t cook flaxseed oil, but many still are heating olive oil to temperatures that damage the fatty acids and create carcinogenic compounds. When cooked oil begins to emit smoke (known as the smoke point), it is a sign that the oil has begun to degrade. Take a moment to learn what oils to use when frying, sautéing, wok-frying, baking at high temperatures, and searing food, and choose an oil that has a high smoke point. As you notice from the chart that follows, refined oils have a much higher smoke point than unrefined oils and are the best choice when cooking at high temperatures.

Note: The normal temperature range for frying is 325°F to 375°F

Cooking Oil

Smoke Point

Avocado (refined)

520 degrees

Almond (refined)

495 degrees

Grapeseed (refined)

485 degrees

Light olive oil (refined)

468 degrees

Super canola* (refined)

450 degrees

Super high-oleic * safflower oil (refined)

450 degrees

High-oleic sunflower oil (refined)

450 degrees

Peanut oil (refined)

440 degrees

Sesame (refined)

410 degrees

*Made by Spectrum Naturals*

Next, keep a selection of healthy oils ideal for medium or lower temperatures (no more than medium temperature on your stovetop). Use these oils to lightly sauté vegetables, to prepare sauces, and to bake at low temperatures: 

Cooking Oil

Smoke Point

Coconut oil (unrefined)

350 degrees

Sesame (unrefined)

350 degrees

High-oleic safflower oil (unrefined)

320 degrees

High-oleic sunflower oil (unrefined)

320 degrees

Butter (organic)

300 - 350 degrees

Extra-virgin olive oil (unrefined)

250 - 325 degrees

Hippie Wisdom
As is the case with all foods, quality comes with a price tag.  Most supermarkets sell inexpensive yet highly refined oils that have lost much of their nutritive value (the major exception is extra virgin olive oil). Buy oils that are expeller-pressed and organically grown when possible, and that are packaged in smaller containers. Keep oils refrigerated or in a dark pantry (light and oxygen accelerate spoilage). Avoid reusing cooking oils because unhealthy byproducts can be created when oil is reheated. Many restaurants reuse their oil multiple times when frying and most fast-food chains still cook with hydrogenated oils.

Experiment with new oils. Here are my favorites:

1. Everyday oil extra-virgin olive oil (many different tastes depending on region that the olives are grown). Avoid heating at temperatures higher than low-medium. Do not bake with extra-virgin olive oil.
2. Stir-fry light olive oil (from natural food store), grapeseed oil
3. Indian/Thai sesame oil (unrefined), coconut oil (virgin)/coconut milk
4. Baking light olive oil, Spectrum canola

Choose snack chips cooked with high-oleic sunflower or high-oleic safflower oil. Use moderation with all oils, particularly with those containing more saturated fat (butter, coconut oil, and palm oil). Choose extra virgin olive oil for making sauces and dressings but avoid using when baking at 350°F or higher temperature.

- Greg Hottinger, MPH, RD