Does Heating Olive Oil Make It a Trans-Fatty Oil?

Reader question… “I notice you use olive oil… I can’t remember the source, but somewhere I read that olive oil, while a ‘healthy’ oil, is best cold, that when you heat it, it tends to make it’s own transfats.” –Elwin

I had read this too, so I did some research and found extensive information about this topic in particular and olive oil in general on The Olive Oil Source. They say that this idea of olive oil becoming a trans-fatty oil when heated is a MYTH. The following information on this subject is reproduced from one of their recent articles and is posted following their attribution and hyperlink policies:

From The Olive Oil Source:

Olive oil is a great oil for cooking. Strong flavored olive oils can be used for frying fish or other strong flavored ingredients. A mellow late harvest Mission variety oil could be used in baking a cake. Olive oil has a high smoke point, 410 degrees F, and doesn’t degrade as quickly as many other oils do with repeated high heating. Use a variety of healthy vegetable oils when preparing food and incorporate a good extra virgin olive oil when you want its health benefits and wonderful Mediterranean flavor.

There are some myths which have recently circulated about olive oil which we are constantly answering via email and our newsletter. Olive oil has been used for thousands of years and is one of the cornerstones of the healthy Mediterranean diet.

Olive Oil Myth: Heating a cooking oil will make it saturated or a trans-fatty oil.

The Facts: As far as making a saturated fat, according to Dr. A. Kiritsakis, a world renowned oil chemist in Athens, (Book – OLIVE OIL FROM THE TREE TO THE TABLE -Second edition 1998), all oils will oxidize and hydrogenate to a tiny degree if repeatedly heated to very high temperatures such as is done in commercial frying operations. Olive pomace oil and virgin olive oil are both highly monounsaturated oils and therefore resistant to oxidation and hydrogenation. Studies have shown oxidation and hydrogenation occurs to a lesser degree in olive oil than in other oils. But in any case, the amount of hydrogenation is miniscule and no home cook would ever experience this problem.

The large refinery-like factories which take unsaturated vegetable oil and turn it into margarine or vegetable lard do so by bubbling hydrogen gas through 250 to 400 degree hot vegetable oil in the presence of a metal catalyst, usually nickel or platinum. The process can take several hours. You cannot make a saturated product like margarine at home by heating olive oil or any other vegetable oil in a pan. We don’t know where this weird notion has come from. For more see our olive oil chemistry page.

Changing a cis-fat to a trans-fat does not occur on a home stove.

Written by Shirley | Filed Under Household Hints & General Information

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