riceburners2001

so, i had a argument with my dad, i dont kno how it came up about...but here it is.....

my dad claims: when [cooking] oil touches air for a long period of time, it reacts to the oxygen in the air so it somehow "oxidize" older the oil gets, its more harmful to human body.......

so than i told him wtf, why doesnt cooking have expiration date?? (one i checked only had "best used before xx/xx")

i think there is no way this is true... but u never kno............
anyone have the answer?

VTEC_Junkie

i can't tell you if it's true or not, but even if it is so, the surface area of actual oil that's in contact with air is very small, and usually oil doesn't get to sit for a very long time before it's used. and even if it sits in a bottle for a lengthy period of time, the bottle with the cap tightly screwed on is air tight for the most part, so the amount of air that can contact the oil is finite. furthermore, except when oil is used for dressing, it usually gets heated up on the stove, oven, etc., which i'm sure affects the "oxidized" oil somewhat, unless the oxidized oil is eternally stable over a huge range of high temps. personally, i wouldn't worry too much about oil causing cancer. i'd be more concerned about excessive oil in your diet affecting your cardiac health.

jah

get a life, dont do your dad.

cyber_x

Your dad is right. Cooking oil has polyunsaturated fats that are susceptible to oxidation (addition of an oxygen atom or loss of a hydrogen atom). As it sits around in the air, especially under heat or sunlight, the polyunsaturated fat will oxidize and the oil will slowly go rancid. Rancid oil doesn't taste as good and isn't as good for the body. Most cooking oils have antioxidants to mitigate the oxidation process, though.

As an aside, oxidation is also responsible for a lot of other stuff that happens in our world. It's thought to drive aging and certain diseases, and is also the process that leads to rust.

VoIPA

It also leads to that freezer-burn taste in stale old beer.

Penforhire

I'm with Cyber X, dad is right. It doesn't take much air or exposure-surface either. Reducing temperature can slow the process. That is why health experts tell you to keep your olive oil in the fridge.

Will

oils in general are very bad for you, especially vegetable oil. Oil that is repeatedly heated (like the goop frenchfries are cooked in in fast food joints) is the worst, period. The heating breaks down the oil to the point that free radicals are shaken loose and mess you up internally. The best oil to use for cooking is "cold pressed extra virgin olive oil". Oil exposed to air I wouldn't worry about, as long as it is capped. It's oil that is re-heated that is toxic.

riceburners2001

i didnt kno cooking oil oxidize!! i hate it when im wrong........
oh well i just wont tell him his right

NFRs2000NYC

Your dad is right. Cooking oil after use has A LOT of carcinogens. The problem is, unlike tobacco, carcinogens in oil make it taste GOOD. This is why many good fries/burger places keep their oil for a long time (up to 10 years!)

Like everything in life today, its bad for you.