Do the Properties of Oils Change if They're Cooked?
Someone told me a while ago that if you cook with olive oil (in a curry, for example) that its properties change compared with using it in a cold dish (e.g., salad dressing).
Firstly, is this actually true of olive oil, or any oil, for that matter? If so, how are things like the vitamins, antioxidants or saturated/unsaturated fat balance of a particular oil changed when it's cooked?
Best Answer
Usually this is said specifically about extra virgin olive oil. The reasoning is that extra virgin oil is pressed cold and processed without heating in order to preserve specific flavor profiles in the finished product. Cheaper oils are extracted using heat to maximize extraction, but lose some of these flavors. Generally heating is discouraged because you're paying a premium for unheated oil, so using it in hot applications would defeat the purpose.
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Quick Answer about "Do the Properties of Oils Change if They're Cooked?"
When heated repeatedly, changes in physical appearance of the oil will occur such as increased viscosity and darkening in colour [1], which may alter the fatty acid composition of the oil. Heating causes the oil to undergo a series of chemical reactions like oxidation, hydrolysis and polymerization [2].Does oil change when cooked?
Cooking with an oil will not change its fat composition. Olive oil's percentage of monounsaturated fat remains the same after heating, even to high temperatures.What happens to oils when they are cooked?
After just a single exposure to frying temperatures, vegetable oils begin to break down to free fatty acids and glycerol. As free fatty acids increase in the oil, its smoke point declines rapidly. The longer oil is used for frying, the lower its smoke point.Does olive oil Lose Its properties when heated?
The flavor compounds in Olive Oil are delicate and will evaporate when heated. Furthermore, heating olive oil does not damage the health benefits but it will make the olive oil lose flavor. Overall, Olive Oil is safe to cook with. Heating Olive Oil will not destroy the health benefits or turn olive oil unhealthy.Does oil become unhealthy when heated?
When fats and oils are exposed to high heat, they can become damaged. This is particularly true of oils that are high in polyunsaturated fats, including most vegetable oils like soybean and canola.What If You Forget To Change Your Oil?
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Answer 2
These links have a lot of information on them:
http://en.wikipedia.org/wiki/Cooking_oil
http://www.martinfrost.ws/htmlfiles/oct2008/cooking-oils.html
This link specifically answers - Why it's best not to cook with extra virgin olive oil
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