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View Full Version : heat kills good fat right?



Frankster
08-17-2001, 02:38 PM
well.. it does doesn't it? heat destructures good efa's and turns it into saturated fats? right? we all know that.. my question is... if that's the case .. how can the fat in fish be good fat?.... To me it seems like a myth.. because you would have to eat it raw in order to get the good fat.

*takes a bite out of live tuna fish*

Ronan
08-17-2001, 02:55 PM
poly unsaturated fats turns to saturated fat when cooked in heat


monosaturated fat does not change its chemical structure.

Wizard
08-17-2001, 02:57 PM
No..
Heat destructures good efa's and turns it into trans fats
which are devil. :evillaugh
But not all fats..
Olive oil doesn't turn into trans fatty acids when heated and for this reason it's unique.
As for omega3 found in fish oils,they don't turn into trans.
Omega 6(vegetable oils) turn into trans very fast.

Frankster
08-17-2001, 04:20 PM
cooooollll.. thank you

Jane
08-17-2001, 04:31 PM
sooo...if I use an oil that is high in polyunsaturated fat for say, a stir fry, ill make a meal high in trans fat? would that mean I should use olive oil instead of peanut or canola or corn oil?

Wizard
08-17-2001, 04:35 PM
Yes,it's healthier to cook with olive oil as it has the bigest monounsaturates concentration (up to 70%).
Polyunsaturates are better in salads.(dressings)

Tryska
08-17-2001, 06:46 PM
Originally posted by Blackalpha
No..
Heat destructures good efa's and turns it into trans fats
which are devil. :evillaugh
But not all fats..
Olive oil doesn't turn into trans fatty acids when heated and for this reason it's unique.
As for omega3 found in fish oils,they don't turn into trans.
Omega 6(vegetable oils) turn into trans very fast.


hate to nitpick blackalpha, but actuallt it doesn't turn them to trans fats....it turns them to lipid peroxides, which are the free radicals from hell. other oils (polyunsats, efas) which turn rancis also begome lipid peroxides, so don't use rancid oil. if your cooking use either olive or canola, although my preference is still olive.

a transfat is essentially a polyunsat which has had an artificial molecule added (by dipping a metal into it to get the added hyrdogen molecule -i think?) so that that polyunsat will be solid at room temperature. (ie - Crisco)

but other then that teeny error, you are on point...transfat = the devil, do not cook with EFAs.

you would actually be better of cooking with lard, if that says something...*lol*

The_Chicken_Daddy
08-18-2001, 10:15 AM
so is it best to fry with monounsaturated sources?

Jane
08-18-2001, 10:49 AM
Ok, I THINK I get it, but just to make it nice and clear, would someone please post a list of "stuff you can use to stir-fry" ranging from best to worst?

Would the list start with something like water or olive oil maybe? And would corn oil be on the bottom? :help:

the doc
08-18-2001, 12:19 PM
any oil brought to its flashpoint is being oxidized similar to what tryska said.

Heating oils will not turn them from unsat to sat, this is impossible.

Polyunsaturated fats are more easily oxidized and have lower flashpoints. It has to do with the number of allylic positions in the acid chain.

Mono unsats have higher flashpoints, less allylic hydrogens and thus are more robust.

sat fats are quite stable to high heat and have the highest flashpoints. Containing no allylic hydrogens they are quite resistant to heat induced oxidation.

Thermal isomerization from cis to trans fats happens regardless of whether it is mono or poly unsats, but only at very high temperatures. For most oils this will be at temps higher then its flashpoint. In the lab we would perform this isomerization under inert atmosphere to avoid oxidation. Most oils start to combust before thermal isomerization occurs.

Bottom lines: one wants to avoiding heating oils to smoking temperatures, also, when you want to fry use an monounsat oil. Actually the best for this purpose is sat oil (ie lard) but no one wants to eat that anymore.

Tryska
08-18-2001, 01:20 PM
well alright doc....*lol* your chemistry is showing....great explanation.....

Wizard
08-18-2001, 02:07 PM
:eek: Yeah! His analysis was impressive!
Thanks for the correction Tryska.
I never liked chemistry... :D