Selecting a Healthy Cooking Oil and Reusing it Safely

by Sarah healthy fatsComments: 68

healthy cooking oil is not used as biofuelIf you talk with anyone who has ever worked at a fast food joint, chances are that one of the things they will tell you is how gross the frying oil gets as it is repeatedly reused.

Even if procedures are supposedly in place to prevent the continual reuse of disgustingly rancid cooking oil, restaurant managers frequently ignore them and push the envelope as much as possible to keep cooking oil costs down.

While this vegetable oil is great for fueling automobiles, it’s not at all good for your health, certainly not as a healthy cooking oil!

The scary truth is that restaurant cooking oil is rancid before it is even used and this is because the oils of choice are factory processed and high in polyunsaturates – oils that were never designed to be heated at all much less fried in.

The cheap oils of choice for restaurant frying are canola or soy oils – both already rancid from factory processing even if marketed as transfat free.  In addition, both canola and soy oil are most likely genetically modified unless organic and what restaurant uses organic cooking oil?  Not even Chipotle last time I called and checked.

You see, it doesn’t really matter if a restaurant serves a meal of sustainable organic fare sourced locally.  If it’s cooked in soy or canola oil, which is what Chipotle uses for everything except the chips (which are fried in sunflower oil which a no-no polyunsaturate for cooking too), then the meal is going to make you feel terrible later anyway – at least it makes me feel terrible which is why I don’t value eating at Chipotle over any other standard restaurant.

But Wait!  Isn’t Canola Monounsaturated Like Olive Oil?

While it might be argued that canola has a high amount of monounsaturated fats which are more stable for frying than a predominantly polyunsaturated oil like soy, canola also has a large percentage of delicate omega 3 and omega 6 polyunsaturated fats which are almost certainly rancid upon leaving the factory (there are other ways to destroy oils besides hydrogenating them!) and denatured to an even greater degree by the time something is inappropriately fried in them at a restaurant!

If a restaurant claims to be using olive oil (which is low in polyunsaturates) for cooking, be on the alert.  It is most likely not 100% olive oil.   Restaurant grade olive oil is cut with GM canola oil or a cheap polyunsaturated oil.

Healthy Frying at Home

Even though fried foods at restaurants have a bad rap and for very good reason, do not despair – frying at home can be a much healthier experience!

All that is required to safely cook and fry in oils at home is selecting the correct type of fat and keeping the heat below the smokepoint.

Traditional cultures seemed to know instinctively which fats were best for cooking and these fats are almost without exception animal fats.

If you are uncertain about whether a fat is safe to cook in or not, just google it and note the percentages of saturated, monounsaturated, and polyunsaturated fats (all fats and oils are a mixture of the three).

If the percentage of polyunsaturates is very low as is the case with animal fats, then it is a good bet that the oil is fine to cook or even fry in.

Example:  I am asked frequently whether grapeseed oil is a good cooking oil.  It is certainly marketed as a heart healthy oil, but what is the truth?

The answer is that grapeseed oil is not a good oil to cook in and certainly not to fry in.  It is very high in polyunsaturates (nearly 75%) which most Americans are already overdoing with their predilection for processed foods which are loaded with rancid polyunsaturates.

A better choice would the be a traditional fat like tallow which is the usual fat I use for frying.

Tallow is less than 5% polyunsaturated.

In a nutshell, as a general rule of thumb if you are not sure about a particular cooking oil, let your fingers do the walking and make sure it is very low in polyunsaturates before you select it for cooking or frying.


Can You Reuse a Healthy Cooking Oil?

While you may remember Grandma reusing bacon grease or leaving a dish of used cooking oil by the side of the stove for later use, be aware that even healthy oils can have plenty of free radicals in them after cooking that can harm your health.

Here are the two things to keep in mind before reusing any cooking fat – even if traditional:

  1. Did you exceed the smokepoint for the particular fat you selected for frying?  Be sure to know what the smokepoint of your cooking oil is and even test it with a frying thermometer before starting to cook the food with it.  Exceeding the smokepoint ensures that free radicals will be in your food even if you cooked with a very healthy, traditional fat.    If you did exceed the smokepoint, it’s definitely best to not reuse the oil!  Even high smokepoint oils can be damaged when the heat gets too high.
  2. Are there a lot of bits of food in the oil after you finished cooking?  Even if you stayed below the smokepoint for the particular oil you used, having food particles left in the oil will reduce the smokepoint of the oil if it is used again.   If you want to be super safe, it is best to not reuse the oil at that point.  If budget reasons require the use of the oil again, be sure to filter out the food particles as best you can. This way, it won’t contain food residue which will cause a significant drop in the temperature of the smoke point and increase free radical production.

Want to Know More About What Fats to Eat and What Fats to Avoid?

Check out my eBook Get Your Fats Straight to get the skinny on fats in an easily understandable, comprehensive format.


Sarah, The Healthy Home Economist

Sources and More Information

Cooking with Olive Oil: Yay or Nay?

Traditional and Unusual Uses for Olive Oil

Is Rice Bran Oil a Healthy Fat?

Why Pumpkin Seed Oil is Not Good for Cooking

Caution When Using Chicken Fat for Cooking

How Argan Oil Benefits Health

Red Palm Oil Benefits Rival Coconut Oil

Walnut Oil: Healthy Sub for Flax Oil

The Many Shades of Palm Oil

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