Oil me up baby!

One of the things I get asked quite frequently is" why is there sometimes a funny taste after I fry something?"
My fist response is a question as well: What kind of oil are you using?

Oil has a smoke point. The smoke point is the temperature at which the oil actually starts to degrade, and releases free fatty acids ( a.k.a. free radicals) into the food it is being used to cook. This is a bad thing, not only for the flavor, but for your body as well. These free fatty acids can potentially become carcinogenic.

The most basic chemistry of veggie oil is that there is a glycerol backbone, and 3 fatty acids connected to it ( there are a few other already existing free fatty acids, less than 1% is acceptable) Once you begin to heat the oil, it oxidizes, and begins to break those bonds, degrading the oil. The result of this process is rancid oil. Very unhealthy, and very un-tasty!

So don't saute your chicken in extra virgin olive oil... use something that can stand up better.
For reference- here's a chart for smoke points ( thanks to http://www.thenibble.com/reviews/main/oils/smoke-point2.asp):

200s: Low Smoke Point
225°F: Canola Oil

(Unrefined)
Flaxseed Oil (Unrefined)
Safflower Oil (Unrefined)
Sunflower Oil (Unrefined)

300s: Medium Smoke Point
320°F: Corn Oil (Unrefined)
High-Oleic Sunflower Oil,
Unrefined
Olive Oil, Unrefined
Peanut Oil, Unrefined
Safflower Oil, Semi-Refined
Soybean Oil, Unrefined
Walnut Oil, Unrefined
325°F: Shortening, Emulsified
Vegetable
330°F: Hemp Seed Oil
350°F: Butter
Canola Oil, Semi-Refined
Coconut Oil
Sesame Oil (Unrefined)
Soy Oil, Semi-Refined
360°-370°F: Vegetable Shortening
(Emulsified)
370°F: Lard
375°F: Olive Oil

400s: High Smoke Point
400°F : Canola Oil (Refined)
Walnut Oil (Semi-Refined)
406°F: Olive Oil, Extra Virgin
410°F: Corn Oil
Sesame Oil
413°F: Macadamia Nut Oil
420 F: Cottonseed Oil
Grapeseed Oil
Olive Oil, Extra Virgin
430°F: Almond Oil
Hazelnut Oil
435°F: Canola Oil
438°F: Olive Oil
Rapeseed Oil
440°F: Peanut Oil
Sunflower Oil
450°F : Corn Oil (Refined)
High-Oleic Sunflower Oil (Refined)
Palm Oil
Peanut Oil (Refined)
Safflower Oil (Refined)
Sesame Oil (Semi-Refined)
Soybean Oil (Refined)
Sunflower Oil (Semi-refined, Refined, High Oleic, Refined)
Vegetable Shortening
460°F : Olive Pomace Oil
468°F: Olive Oil, Extra Light

485+: Very High Smoke Point
485°F: Grapeseed Oil
485°F: Tea Seed Oil
490°F: Rice Bran Oil
495°F: Soybean Oil
510°F: Safflower Oil
520°F: Avocado Oil (Refined)