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Healthy Frying Oils


SparrowsFall

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Hi All:

I've been researching fats in diet, and am having trouble finding good information on frying oils. Lots of advice, but mostly vague and missing (and often just incorrect) information.

Short story: Canola and other vegetable oils oxidize and produce free radicals (bad for you), even when they're just sitting there. As temperature increases, so does the oxidation. These unsaturated fats also convert to trans fats (BAD!) with heat.

But I'm having trouble finding any information on the temperatures and durations at which these changes become significant. Everything I find is quite vauge, except for Figure 6 at http://www.canola-council.org/pubs/physprop.html, which suggests that the conversion to trans fats in canola oil is very minor and slow at 190 degrees centigrade--375 farenheit. And it's even quite slow at 425.

Larousse Gastronomique tells me that deep-fry temperatures are between 275 and 360 F--way below most oils' smoke point (though I don't know whether smoke point matters at all to this discussion, though it's what most web sites talke about). Does anybody know whether significant free radicals are developed at these temperatures? According to the link above (which IS from the canola council, but looks pretty reliable nevertheless, if you read through it), creation of trans fats is not a problem at these temperatures.

Another alternative is lard, because saturated fats don't convert to free radicals at heat. (Contrary to what people are forever spouting, increasing saturated fat intake has no correlation to likelihood of coronary heart disease--at least in women; see table 3 in http://content.nejm.org/cgi/reprint/337/21/1491.pdf, which is the gold-standard Harvard study of 80,000 nurses over 14 years. Look at the data before believing this paper's weasely written conclusion, which conflates the effects of trans fats with saturated fats.)

But I've heard that most lard you buy is hydrogenated--like crisco or margarine--so it has to nasty trans fats. Is this true (the hydrogenation, and the trans fats?) Anybody know sources for non-hydrogenated lard?

Love to hear thoughts from people who love to live well--and long.

Thanks,

Steve

"Approach love and cooking with reckless abandon." --Dalai Lama

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You might want to think about using coconut oil which is not hydrogenated and has not colesterol but does have saturated fats in it.

In regards to free radical and smoke point. I usually use the smoke point and then drop by 20 degrees to be safe.

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But I've heard that most lard you buy is hydrogenated--like crisco or margarine--so it has to nasty trans fats. Is this true (the hydrogenation, and the trans fats?) Anybody know sources for non-hydrogenated lard?

Yes, packaged lard may be partially hydrogenated, in which case it contains trans fats, and it is almost always adulterated with preservatives like BHA and BHT. Check the ingredients list. For fresh lard, ask at butchers of the gourmet variety or ones that cater to Latin American or Portuguese clients. "Light, Fluffy: Believe It, It's Not Butter," a New York Times article published in October 2000, claimed that "John F. Martin & Sons of Stevens, Pa., will ship lard by mail for $2 a quart plus tax and shipping; (717) 336-2804." It's also easy to render your own, especially if you can find a butcher who will sell you leaf fat, the crumbly fat that surrounds a hog's kidneys. If you decide to go that route, say the word and I'll post a procedure or two.

Edited by carswell (log)
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Fat is fat, so use the stuff that tastes good. I agree, people are way too worried over saturated vs. unsaturated and etc. The only thing I really worry about is trans-fats, other than that, anything is fair game.

I deep fry in peanut oil, it holds up well, has a good smoke point,a nd if you buy in bulk, it isn't too expensive. I recently tried soybean oil as well, and the results were good, it is also very cheap.

He don't mix meat and dairy,

He don't eat humble pie,

So sing a miserere

And hang the bastard high!

- Richard Wilbur and John LaTouche from Candide

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Unless you have a subscription to NEJM, you won't be able to download that paper. But I found a copy of it here:

Hu et al, 1997. Dietary fat intake and the risk of coronary heart disease in women. New England Journal of Medicine 337, 1491-1499.

Another alternative is lard, because saturated fats don't convert to free radicals at heat. (Contrary to what people are forever spouting, increasing saturated fat intake has no correlation to likelihood of coronary heart disease--at least in women; see table 3 in http://content.nejm.org/cgi/reprint/337/21/1491.pdf, which is the gold-standard Harvard study of 80,000 nurses over 14 years.

You mean, the relative risk for CHD after controlling for intake of monounsaturated,

polyunsaturated, and trans-unsaturated fats? I thought this was odd, but it looks like you're right. The relative risk of CHD in the highest quintile of saturated fat consumption was only 1.07 times as high the risk of CHD in the lowest quintile, and since the confidence interval does not exclude 1, there is no statistical difference.

Interesting!

Conversely, the intake of trans-fat does seem to have an independent effect on CHD risk, even afte correcting for intake of monounsaturated, polyunsaturated, and trans-unsaturated fats. The highest quintile of consumption had a relative risk of CHD 1.53 times that of the lowest quintile, and the confidence interval does exclude 1.

Though Hu et al do state that saturated fat intake is associated with CHD risk, they point out that "The observed relation for saturated fat was much weaker than that predicted by international comparisons,1 suggesting that the international analysis is seriously confounded by other lifestyle factors.3 However, our findings are consistent with the small-to-negligible effect predicted by metabolic studies of the relation of diet and blood lipid levels." The irony is that, in Hu et al's own study, the relative risk of CHD according to sat fat intake dropped almost to nothing when controlling for other confounders, suggesting that the association between saturated fat intake and CHD may be entirely a product of confounding (which doesnt mean that saturated fat is harmless, only that, contrary to popular belief, it is not more harmful with respect to CHD than other fats).

SparrowsFall, there was another paper (Mozaffarian et al, 2004) published last year in The American Journal of Clinical Nutrition that provides additional support for Hu et al's data. This study looked at the effect of dietary components on progression of atherosclerosis and stenosis (i.e. hardening) in a group of 235 postmenopausal women over a period of 3 years. Assessment of progression was by x-ray angiography at the beginning and the end of the study. The striking result was that polyunsaturated fat intake and high glycemic carb intake were both associated with atherosclerotic and stenotic progression, while saturated fat intake was not.

Mozaffarian et al, 2004. Dietary fats, carbohydrate, and progression of coronary atherosclerosis in postmenopausal women. American Journal of Clinical Nutrition 80, 11175-1184.

See also the commentary by Knopp and Retzlaff:

Knopp and Retzlaff, 2004. Saturated fat prevents coronary artery disease? An American paradoxAmerican Journal of Clinical Nutrition 80, 1102-1103.

Looks like another piece of conventional dietary wisdom may bite the dust!

"If you hear a voice within you say 'you cannot paint,' then by all means paint, and that voice will be silenced" - Vincent Van Gogh
 

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Patrick S, thank you, thank you, thank you for providing the references to those studies. I always felt in my bones that naturally occuring fats were the way to go. Many years ago, I quit with the margarine and went back to butter. I started making my own lard, my attitude being, "to hell with it, it tastes good." I quit worrying about the coconut milk in my Thai curries. My reasoning wasn't based on data. I just figured that molecularly manipulated fats, i.e. trans fats, just had to be wrong. We didn't evolve with them.

Linda LaRose aka "fifi"

"Having spent most of my life searching for truth in the excitement of science, I am now in search of the perfectly seared foie gras without any sweet glop." Linda LaRose

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Good questions, Steve! Good answers, Patrick! Just on one point - Fifi and I both make our own lard, and I don't use leaf fat, just clean white pork fat, and I think that's how Fifi does it too.

Personally, I use olive oil for almost everything, except for using Chinese peanut oil when I want that peanut flavor. But then, I'm deep-fry phobic, so I'm only sauteeing or wokking, which is probably a whole nother thing.

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You are right Abra. I can't find leaf fat. Heck, I have a hard enough time finding good dense, white pork fat. The last package I bought at my Fiesta Mart had enough meat in it that I ended up making carnitas. :laugh:

The only hard part of rendering your own lard is finding the fat.

Linda LaRose aka "fifi"

"Having spent most of my life searching for truth in the excitement of science, I am now in search of the perfectly seared foie gras without any sweet glop." Linda LaRose

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Hey All:

Sorry to start a topic then disappear; I had eG set up to track this topic, but haven't gotten emails. Glad I stopped by.

Thanks for all the replies. Patrick, thanks for digging up more research. NEJM registration is free ('s enuf to get at this article anyway), but thanks for the open link. The conclusion from the Mozaffarian study, that "a greater saturated fat intake is associated with less progression of coronary atherosclerosis, whereas carbohydrate intake is associated with a greater progression" (in women) is great to hear in such unqualified terms. Is there a Dr. Atkins in the house? <g>

The key message, of course, is to stay the hell away from hydrogenated margarine. Talk about decades of really bad advice floating around! Butter *is* better!

Here's a whole string of items and related questions.

Does anyone know of other data/info on the temperatures and durations at which vegetable oils convert to free radicals? To trans fats? Is this really not a problem at all at the relatively low temperatures of deep frying? (At least for home cooks, who generally don't keep using the fat for hours or days at a time--we use it then lose it.)

Is there a correlation between an oil's smoke point and the temperature where it starts generating lots of free radicals?

How about the really important part: taste and texture? See this excellent NYT article:

http://www.nytimes.com/2005/02/13/business...print&position= (still free to view when I posted this).

They hydrogenate oils for two reasons: 1) to make them solid at room temperature, so the oreo filling doesn't go soft, and 2) to make them more "stable" when frying--so smoke and bad flavors develop more slowly and the oil can be used longer. Do we, as home cooks, care?

My ex used to use crisco for making icing, and it was good--less greasy than butter. Is lard as good as crisco?

For frying, the only advantage of crisco is using it for a long time. So I don't think we care. What's the best frying fat right out of the container?

Please, firsthand reports on crispiness, greasiness, etc. with different oils? Is this (liquid canola) why my fritters aren't as crispy as I'd like them to be?

vinelady:

>You might want to think about using coconut oil which is not hydrogenated and has not

>colesterol but does have saturated fats in it.

The "tropical" oil hysteria in the 80s, by the way, was just that, instigated quite intentionally through an intensive advertising/PR campaign by the domestic oil producing organizations. It worked.

I read somewhere that palm oil was one of top few oils used in the world, so it shouldn't be so expensive. There are cheap sources on Froogle, but all targeted to soapmakers. ??

Here's a source of coconut oil at $13.30/gallon: http://www.vittitow.com/product_info.php?r...roducts_id=1322.

Does anyone have any experience cooking with coconut oil (except for popcorn)? Taste? Texture?

Shirley Corriher (Cookwise p. 177) says that the oils with most saturated fat are coconut (87%), butter oil (62), palm and beef tallow (50). Lard's actually down at 40%.

Unsaturated fats, which are usually good for your heart (see the nurse's report), are bad when they get *too* hot (free radicals and trans fats) or are hydrogenated (trans fats). Lard is 58% unsaturated. Peanut's 78%. Coconut is only 8%. (This is why even lard, when hydrogenated, contains trans fats.)

Cholesterol levels: lard (12%), chicken fat (11), beef tallow (14), and butter (33). Not that I care; limiting dietary cholesterol is a *very* weak lever for controlling serum cholesterol, especially if you're trying to increase HDL while reducing LDL. This helps explain why the the nurse's study also shows that *animal* fat is not bad for your heart. More decades of bad advice. For sensible cholesterol control, see http://health-heart.com.

On that note, I have to share that I just had a delicious serving of homemade lobster bisque--made with cream, of course. Following my daughter's birthday dinner, I pulverized the shells in the cuisinart, then subjected them to extortionate levels of heat in the pressure cooker (thanks, Abra!) for forty-five minutes--best extraction I've ever gotten. The damn kids ate all the lobster meat, so I had to add in frozen tails from Trader Joe's at $20/pound--not so bad cause you don't need much.

Patrick s:

Though Hu et al do state that saturated fat intake is associated with CHD risk, they point out that "The observed relation for saturated fat was much weaker than that predicted by international comparisons,1 suggesting that the international analysis is seriously confounded by other lifestyle factors.3 However, our findings are consistent with the small-to-negligible effect predicted by metabolic studies of the relation of diet and blood lipid levels." The irony is that, in Hu et al's own study, the relative risk of CHD according to sat fat intake dropped almost to nothing when controlling for other confounders, suggesting that the association between saturated fat intake and CHD may be entirely a product of confounding (which doesnt mean that saturated fat is harmless, only that, contrary to popular belief, it is not more harmful with respect to CHD than other fats).

Exactly. (The "international comparisons," BTW, refers to the [in]famous seven-country study that failed so miserably to control for so many factors.)

Sez Hu:

"higher dietary intake of saturated fat

and trans unsaturated fat is associated with an increased

risk of coronary disease"

But they confute two variables here. The risk is all from the *trans* fat. They just can't bear to admit that they've been giving bad advice for so long.

This, by the way, goes a long way to explaining the French conundrum.

fifi:

>I just figured that molecularly manipulated fats, i.e. trans fats, just had to be wrong.

>We didn't evolve with them.

Yeah. We evolved on the African savanna, glutting on animal fat whenever we could lay our hands on it (without getting eaten), and devouring fruits and vegetable when possible, in season. The thing we didn't evolve with was plentiful grains from agriculture. Those who could survive on the former diet were more likely to pass on their genes. There hasn't been time for natural selection to evolve a human that thrives on heavy carb diets.

OTOH: we didn't evolve eating lots of plant oils, either, but they're definitely good for us. Go figger.

Phew. I'm done.

Steve

"Approach love and cooking with reckless abandon." --Dalai Lama

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Is there a connection between hydrogenation occuring at high heat and oxidization/polymerization? Are they one in the same? The reason I ask is that I've done some research on polymerization in hopes of better understanding the seasoning of frying pans and I think it might apply here.

From what I understand, polymerization is the inevitable result of an aging fat. If one leaves an oily frying pan in the cupboard for a year or more, you'll see brown deposits on it that can't be washed off with soap and water, aka polymerized fat. The exact same thing occurs with a frying pan seasoned in a 350 oven. The only difference is that heat accelerates the process. Even in a refrigerator, polymerization can occur. Take for instance, EVOO. Fresh EVOO when chilled, is still clear. After a few weeks, it will start to turn cloudy. Give it enough time and it will start to turn solid. This, as far as I know, is polymerization and is a part of the process of a fat going rancid.

I haven't done a lot of research on free radicals, but I do know rancid fat is both extremely unpalatable and unhealthy. Think of how olfactorilly unnappealing a trip down the dog food aisle is. Unlike our canine companions, humans aren't engineered to consume rancid fat. We're hardwired to be revolted by it. Heat/light/oxygen accelerate oxidization. Partially polymerized fat is rancid fat, and is thus to be avoided.

Putting it all together:

1. Use the freshest fats possible

2. Never re-use a fat to fry with

3. Use saturated/trans fat free fats (saturated=stable=less prone to oxidization)

4. Limit exposure to air by using deep narrow frying implements

This is a lot of conjecture and I may be connecting dots that should't be connected, but that's how I see it.

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