Is reusing cooking oil safe?

here i got this from GO ASK ALICE:

Reusing cooking oil has been done for ages. There really isn't a problem, if done properly. The greatest hazard is allowing the fat to become rancid (spoiled) and deteriorated to the point it produces undesirable flavors and odors. Besides ruining what would have been a perfectly good meal, rancid oils also contain free radicals that are potentially carcinogenic.

To understand how to best re-use oil, it is important to know about smoke points ? the temperatures at which oil begins to decompose. If you heat oil to a temperature that is too high, it produces smoke fumes. Acreolin, a substance that makes your eyes burn, is given off as well.

The optimal temperature to fry foods at is 190?C (375?F). At higher temperatures, the food will burn on the outside, and at lower temperatures, the food absorbs too much oil and tastes greasy. Different oils have different smoke points. Oils with higher smoke points are better for frying. The following is a list of smoke points:

Type of Oil Smoke Point Temperature
safflower oil 265?C
sunflower oil 246?C
soybean oil 241?C
canola oil 238?C
corn oil 236?C
peanut oil 231?C
sesame oil 215?C
olive oil 190?C
lard 183 - 201?C*
(*varies depending on the diet fed to hogs and the part of animal fat that is derived)

Each time the oil is re-used, the smoke point becomes lowered. This is due to:

foreign matter in the oil (such as batter)
salt
the temperature to which the oil was heated
exposure to oxygen and light
length of time the oil remained heated
the number of times the oil was reused
Combining different types of oils also lowers the smoke point.

When oil becomes deteriorated, it appears dark and thick (viscous). It may have an off odor, and smoke appears before it reaches 190?C. If the oil smells funky and old, better to toss it away and replace it with fresh oil.

To re-use oil safely, use these tips:

Strain it through a few layers of cheesecloth to catch any food particles. Be careful with hot oil, though, because you can easily get burned.
Shake off excess batter from food before frying it.
Use a good thermometer to fry foods at 190?C.
Turn off the heat after you are done cooking. Exposing oil to prolonged heat accelerates rancidity.
Don't mix different types of oil.
Store oil in a cool, dark place.
Avoid iron or copper pots or pans for frying oil that is to be reused. These metals also accelerate rancidity.

I think it is a smart idea to NOT take chances reusing oil.

This shouldn't really be much of an option ANYWAYS, since you shouldn't be deep frying often.

Is cooking your food in oil safe?

not in the long term.

bump

This is basically info for restaurant owners. For home use if you HAVE to deep fry I would suggest using EVOO, avacado, or coconut oils. The evoo and avacado because of the high mono fats that are more resistant to molecular changes from heat and coconut because a saturated fat is basically not effected by heat. IMO

[QUOTE=baarat;27321961]This is basically info for restaurant owners. For home use if you HAVE to deep fry I would suggest using EVOO, avacado, or coconut oils. The evoo and avacado because of the high mono fats that are more resistant to molecular changes from heat and coconut because a saturated fat is basically not effected by heat. IMO[/QUOTE]


Deep frying in EVOO would prove costly though.

If you deep-fry correctly, dont get me wrong, its still an unhealthy way of eating, but if done correctly its not as bad. The oil has to be at a perfect temperature. so when cooking, lets say battered fish, if done correctly, when you drop the fish in, because of the temp of the oil, the batter cooks instantly, while the fish poaches inside, if the temp is too low, the oil will get to the fish and this makes it unhealthier. Personally i think there are worse ways to cheat.

EVOO is not a very good oil for cooking at high temps

[QUOTE=Swaggydoo;27324091]Deep frying in EVOO would prove costly though.

If you deep-fry correctly, dont get me wrong, its still an unhealthy way of eating, but if done correctly its not as bad. The oil has to be at a perfect temperature. so when cooking, lets say battered fish, if done correctly, when you drop the fish in, because of the temp of the oil, the batter cooks instantly, while the fish poaches inside, if the temp is too low, the oil will get to the fish and this makes it unhealthier. Personally i think there are worse ways to cheat.[/QUOTE]

Your right Swaggy, it would be expensive if you did it 2 to 3 times a week......personally I haven't had anything deepfried in more than a year. I used EVOO. Yeah the science behind deepfrying affords little oil to be absorbed if done properly. Bur restaurants usually lower the temp to preserve the oil.....the old food cost thang.LOL

if cleaned up and slightly refined used cooking oil can be turned into an alternative to diesel fuel!
i wouldnt recook with the stuff though!