Cooking with Oils

Oil is an essential part of cooking, it adds flavor, it prevents sticking, it can even bring out certain vitamins from our foods. 

The choices seem to be endless. How do you know what oil to use and when?

Different oils do better under certain conditions based on their individual structure. Some do well with high heat and others should never be heated.

Why does the type of oil matter when cooking?

To begin with, it is important to have a basic understanding of oils and their structure. Each oil's structure is the determining factor on how it will handle heat. For more information on Differentiating Fats please take a look at my previous blog post.

Okay, now that you have read my previous post and are up to speed on fat basics…lets continue.

Every oil has a "smoking point," or the point in which the oil begins to break down and smoke when heated. When this happens the oil is rancid. It begins to oxidize and produce free radicals. The toxic chemical Acrolein is also released into the smoke. This chemical has been linking to Lung Cancer.

Saturated Fats

These fats are solid at room temperature and withstand high heats. Because of their stable nature they resist oxidization.

Monounsaturated Fats

Liquid at room temperature, but solid when refrigerated. These are slightly more unstable, but many can be used in cooking at medium and high heats. These are often nut oils.

Polyunsaturated Fats

What does "refined, semi-refined and unrefined" mean?

These oils are also liquid at room temperature, but are also liquid when refrigerated. These oils are very unstable, and typically become rancid very easily. In general these are not cooking oils, but are wonderful as a finish oil to drizzle on after cooking.

Another step when choosing your cooking oil is to stick with unrefined oils. Refining the oil can make it more stable, but read the process that oils go through to become refined.

The first step in oil extraction involves crushing or grinding oil-bearing tissue to release oil from cells. The second step involves pressing to squeeze oil from crushed tissue. Residues from pressing are usually extracted with solvents such as hexane to remove the remaining oil. The solvent is then removed. To purify these oils, they are further extracted with alkali and heated, degummed, deodorized by steam treatment, and decolorized by treatment with charcoal or clay. Since these procedures remove or destroy vitamin E, synthetic antioxidants like BHT, BHA, and propyl gallate are often added to retard rancidity. Oils may be "winterized" by removing particulate matter that form upon chilling. 

Dr. Robert Ronzio author of Nutrition and Good Health

In the processing and extraction of unrefined oils the seeds are crushed and ground to release oil. The step to extract excess residue from the oil is skipped. This gives the oil a very strong flavor. 

Be aware that "cold-pressed" can mean that chemicals are used in the oil extraction process. Only oils labeled as "unrefined" can claim to truly be pressed without assistance. 

Storing Your Oil

In general, oils should be stored in a dark, cool spot away from direct light and heat. The container should be air tight, and a dark, glass container is preferred. Even stable oils can go rancid in the right conditions. 

Oils should smell like their source. Olive oil should smell like fresh olives, sesame oil like sesame seeds. If you feel your oil smells off, throw it out. Its better to be safe than expose yourself to potential cancer causing chemicals.

A Little on Individual Oils

I want to highlight a couple of the important and popular cooking oils out there. Some of them are talked about as being healthy, others have a bad wrap. I want to talk the pros and cons of each and hopefully help you find the cooking oils that work best for you.

Olive Oil

I wanted to start with Olive Oil, as it seems to me to be the most popular culinary oil out there. I know I personally love it and use it frequently.

I feel like when I go to purchase cooking oils, I am bombarded by the thousands of different Olive Oils. How do we navigate through this market?

All Olive Oil begins with the crushing, pressing and extraction of oil from the olive fruit. From there it becomes one of four commercial grades

The best of which is unrefined, Extra Virgin Olive Oil from a reliable source.

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Olive Oil is a Monounsaturated fat that can withstand Medium-High temperature. It has a smoke point between 325-375.

It is a good oil to use in Salad Dressing and as a drizzle (It does have some great health benefits and is a very high source of Omega 9). It does not work well for high heat cooking or anything that you want a good crisp on (frying, stir-fry, roasting, searing meat). If it smokes, its bad. If you are cooking with Olive Oil and you see smoke, you have ruined your oil.

Nutritionally Olive Oil is a high source of Omega 9 Monounsaturated Fatty Acids. High quality Extra Virgin Olive Oil can be up to 85% Omega 9. 

Coconut Oil

Coconut Oil is all the rage. For good reason. Coconut oil is a very stable oil that can be used for a variety of preparations. 

Coconut oil is pressed from the fruit of the coconut palm. It adds a light flavor to foods, and can be used in baking. Like olive oil, look for high quality extra virgin, unrefined oil. that has a clean white color. 

It is a tropical, saturated fat that is stable at room temperature. You can use coconut oil as a substitute for butter in a 1:1 ratio (I like to make my brownies with Coconut Oil).

Coconut Oil is a more stable oil, but it still does not handle high heat cooking.  It can be used for medium heat.  It works very well in baking.

Being a saturated fat, it is less likely to go rancid and has a relatively long shelf life.  It has a smoking point of 350.

Nutritionally, Coconut Oil is a high source of Lauric Acid.  A saturated fat that raised HDL (good cholesterol).

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Canola Oil

Rapeseed is a member of the broccoli family. It has become an extremely popular oil, and even Whole Foods uses it in food preparations.


Its profile seems to show a healthy oil. It contains Omega 3 Fatty acids (11%), and monounsaturated fats similar to those found in Olive Oil.

Rapeseed contains a monounsaturated fat called erucic acid (22%). This is NOT a healthy monounsaturated fat and has shown toxic effect in lab testing. To get around this, the plant has been hybridized and modified to contain less that 2% erucic acid. (80% of canola is GMO)



Canola oil is processed similarly to high fructose corn syrup. The oil is extracted through a combination of heat and chemical methods. Traces of hexane can still be found in the oil even after refining.  It is then refined, bleached and degummed.  During the process the Omega 3 content becomes rancid and deodorizers are used to mask the smell. These deodorizers transform the Omega 3 into trans-fats...most bottles list a total trans-fat amount of less than 0.2%.

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Butter

Butter has gotten a bad rap over the years.  But it is making it's much deserved comeback.  When choosing butter, make sure you are buying butter that comes from happy, healthy grass fed/pasture raised cows. Why?

The milk from cows that are pasture raised (which is seasonally made between May and September), has a must high nutritional profile. Providing CLA (conjugated linoleic acid) in 3-5 times that of grain fed butter. The ratio of Omega 6:Omega 3 in Pastured cows in a 1:1 ratio, while grain fed cows have a 6:3.

Ever notice the color difference between pasture/grass fed butter and commercial butter? Commercial butter is white and grass fed is YELLOW!!! The yellower your butter, the better. This is due to high levels of Vitamin A, (carotene) and Vitamin K2.

Packaged butter has a smoking point of 325-375. It does great in baking, or skillet cooking as long as it doesn't smoke. 

Clarified Butter has a smoking point of 450. It can be used for a wide variety of high heat cooking...but what is clarified butter?

Clarified Butter is butter that has been slightly heated to removed milk solids. You can do this at home my melting butter and allowing the components to separate, and for the water to evaporate off. solids will sink to the bottom and float to the top. Simply skim the top and drain butter, leaving solids on the bottom.  Clarifying butter makes it more stable. It has a longer shelf life and only a small amount of lactose and casein, making it more suitable for those with dairy intolerances.

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Avocado Oil

Avocado oil is made from the fruit of the avocado tree, not the nut like most oils. The process is similar to that of extra virgin olive oil. It is cold pressed and filtered.


Nutritionally Avocado oil is high in healthy monounsaturated fats, Omega 9 (72%). It also contains a high amount of vitamin E.

It is slightly more stable than Olive Oil with a higher smoking point, 475. Making it ideal for high heat cooking, or frying.

It can also be used in salad dressings, or other preparations. It is a very versatile oil.

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Sesame Seed Oil

Sesame oil is derived from the sesame seeds. In was traditionally used as a flavoring oil in Asia, not so much for cooking.

Sesame seed oil can be processed in many different ways, including chemically. It is also often refined to make the oil look and smell clearer.  Cold pressed is the better option if it is labeled.

Sesame oil is high in Oleic (35-50%) and Linoleic (35-50%) fatty acids. While sesame oil is one of the more stable cooking oils, it is still best to store it in a dark/cold place like the refrigerator.

The smoking point for Sesame Oil is between 350-420. The lighter the oil, the higher its smoking point, making it better for high heat cooking.  The darker sesame oils can be used for medium high heat cooking, but as with all oils we have talked about, if it smokes, its ruined. They work very well as a finishing oil to add flavor to dishes, or as salad dressings.

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Peanut Oil

There is a huge push in restaurants to fry in peanut oil. Why? 

There are different forms of peanut oil. It can be refined, unrefined/cold pressed and roasted.

Refined Peanut Oil, like all vegetables oils, has been processed, bleached, and deodorized. This processing gives peanut oil a mild to no taste, and increases its smoking point. This is the form of peanut oil used in restaurant cooking.

Unrefined Peanut Oil, is processed using cold pressing that does not used chemicals in the extraction process. This type of Peanut oil, is mild in flavor, but it is less stable and has a smoking point of 325-350.

Roasted Peanut Oil is a gourmet oil used primarily for flavoring. The peanuts are roasted prior to expelling the oil. This gives it a very robust flavor. 

Nutritionally Peanut oil contains 48% monounsaturated fat Oleic Acid, 33% Linoleic Acid, and vitamin E. 

When cooking, unrefined peanut oil can be used for everyday skillet cooking, as long as it does not reach the smoking point.

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NOTE: Refining oils, as you will have noticed, raises their smoking point, so that they can withstand higher cooking temperatures. That being said, it is good to be well informed on the processing that goes into refining oils, the chemicals used, and the possible structural changes to the oil from the processing.