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.
