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Confit myth

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#1 Kent Wang

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Posted 21 November 2009 - 11:53 AM

This New York Times article on Nathan Myhrvold (discussion topic on his upcoming book) states:

For example, confit, the French technique of cooking slowly in fat, is supposed to impart a unique taste and texture as the fat penetrates the meat.

But Dr. Myhrvold said: “There’s no way it could penetrate. The molecules are too big.”

He said double-blind taste tests proved that the same tasty results could be achieved by steaming and then rubbing some of the fat on the outside.


What do you think of that?

I've confited duck legs several times, and I can't attest to whether the fat enters the meat and actually makes it more flavorful, but it seems that some flavor is lost from the meat and leeched into the fat as there is always a good amount of precipitated "duck jelly". Would steaming prevent this loss of juice?

Nowadays, I confit with sous vide and a very small amount of fat, so it would be similar to rubbing on the fat afterwards.

How about aging? A duck leg aged for a month or so certainly turns more brown, and is perhaps a bit drier. Is it really better?

#2 gfweb

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Posted 22 November 2009 - 01:55 PM

I am not sure what I think of this. Gotta test it.

But I suspect that there will be a wave of protest saying that the old way is the best....well because it just is.

I recall the fairly recent NYT piece on boiling pasta in minimal water and, even worse, adding the pasta to the water when its cold. There were any number of replies on eG saying that this had to be a bad way to cook and that the poster would never ever do it themselves.

Similar posts in response to a method of cooking french fries starting with cold oil. Heresy and blasphemy!

Not that every new way is better, or that one should believe everything that is printed, but without innovation there is no progress.

#3 scott123

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Posted 22 November 2009 - 03:09 PM

Fat can't penetrate meat? What?

Overcook any meat on the planet and then dunk it in any liquid fat. I guarantee you that it will absorb plenty of fat.

Now, as to whether or not confit is effective in taking external liquid fat and actually injecting into meat, that I'm not so sure of.

The power of confit is, imo, extremely slow cooking/not shocking the muscle fibers so they contract and push any liquid out. At least that's the theory that I resonate the most with.

Steam = above 212 = hot = muscle contraction = impaired meat

#4 paulraphael

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Posted 22 November 2009 - 03:15 PM

The power of confit is, imo, extremely slow cooking/not shocking the muscle fibers so they contract and push any liquid out. At least that's the theory that I resonate the most with.


What theory is that? It's a new one on me. I've never heard that muscles contract more or lose more moisture when heated quickly vs. heated slowly. Their final temperature seems to determine how much they contract and dry out.

I can't comment on fat absorption. No experience at all making confit.

Edited by paulraphael, 22 November 2009 - 03:16 PM.


#5 scott123

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Posted 22 November 2009 - 05:21 PM



The power of confit is, imo, extremely slow cooking/not shocking the muscle fibers so they contract and push any liquid out. At least that's the theory that I resonate the most with.


What theory is that? It's a new one on me. I've never heard that muscles contract more or lose more moisture when heated quickly vs. heated slowly. Their final temperature seems to determine how much they contract and dry out.

I can't comment on fat absorption. No experience at all making confit.


I'm not sure where I picked it up, possibly McGee. It's basically that high temps denature the muscle faster, which, in turn, causer greater contraction/greater water loss. If memory serves me correctly, McGee proved this the same time he disproved 'searing/sealing.' I think he seared the meat (on high heat) and there was more moisture loss than when roasting it at an even temp.

#6 Qwerty

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Posted 22 November 2009 - 05:32 PM

Back in the day confitting wasn't really done for flavor it was a way to store meat for long term. You can "pot" a meat and leave it in the jar for essentially monthsm especially to get through the winter. This ripening process in a true confit is what gives it a flavor boost as well.

Nowadays we do it mostly cause it tastes good but back before refrigeration it was a godsend to many people.

#7 paulraphael

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Posted 22 November 2009 - 05:46 PM

'm not sure where I picked it up, possibly McGee. It's basically that high temps denature the muscle faster, which, in turn, causer greater contraction/greater water loss. If memory serves me correctly, McGee proved this the same time he disproved 'searing/sealing.' I think he seared the meat (on high heat) and there was more moisture loss than when roasting it at an even temp.


I don't think that's in McGee. High temps bring the meat up to temperature faster (of course). And high temps above the boiling point cause more evaporative moisture loss (not relevent in steaming or in traditional confit). But as far as how much the muscle fibers contract, I doubt you'll see real differences between meat that's brought up to X temperature in 20 minutes vs. 20 hours.

There will be other major differences ... like how much collagen is broken down, and various kinds of enzyme activity. But that's not the same thing.

#8 scott123

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Posted 22 November 2009 - 06:25 PM

I doubt you'll see real differences between meat that's brought up to X temperature in 20 minutes vs. 20 hours.


Well, regardless of whether or not McGee said it, I still think it holds water (no pun intended). I'll take that bet. Take too identical cuts of meat. Confit one, rinse it, pat dry. Steam the other, pat dry. Weigh both. The confit will weigh more.

#9 Hest88

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Posted 22 November 2009 - 07:25 PM

Back in the day confitting wasn't really done for flavor it was a way to store meat for long term.

Right, that's why this idea confounds me. It's not that I don't think it can't be done if the purpose is just to have something that tastes good, but to completely pooh-pooh cooking in fat is to misunderstand its place in food history.

#10 David A. Goldfarb

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Posted 22 November 2009 - 07:40 PM

I recall the fairly recent NYT piece on boiling pasta in minimal water and, even worse, adding the pasta to the water when its cold. There were any number of replies on eG saying that this had to be a bad way to cook and that the poster would never ever do it themselves.

Similar posts in response to a method of cooking french fries starting with cold oil. Heresy and blasphemy!


McGee's piece on cooking pasta in minimal water didn't demonstrate that it was a good idea, but considered what might happen if one did it. The pasta would get soft and you would have the advantage of starch water for balancing the sauce, and it would be faster to boil less water, but the texture of the pasta might not be as desirable as pasta cooked in a large pot of boiling water.

French fries started in cold oil work surprisingly well as long as you only have to make one batch. If you need to make a lot of fries, then it isn't really an option, because the oil is no longer cold at the end of the first batch.

Edited by David A. Goldfarb, 22 November 2009 - 07:41 PM.


#11 paulraphael

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Posted 22 November 2009 - 11:30 PM

Well, regardless of whether or not McGee said it, I still think it holds water (no pun intended). I'll take that bet. Take too identical cuts of meat. Confit one, rinse it, pat dry. Steam the other, pat dry. Weigh both. The confit will weigh more.


you'd have to find a way to control all the other variables for this experiment to show anything.

#12 Kent Wang

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Posted 23 November 2009 - 10:38 AM

Anyone know the science behind the change in flavor in aging?

#13 slkinsey

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Posted 23 November 2009 - 11:11 AM

My understanding is that it's related to a controlled amount of rancidity. Which is why aged SV confit doesn't develop the same flavors as aged tradtitional confit in a crock.
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#14 OliverB

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Posted 23 November 2009 - 11:51 AM

I doubt the fat penetrates much if any at all, fat doesn't like water and meat is made of a lot of water. I'd guess steaming and then rubbing with some fat for flavor might work. I also think that the fat you cook the meat in will acquire some flavor that it won't have if you just rub duck fat on the meat, which most likely adds to the original recipe experience. If it's duck fat you saved from a roast or something, there's probably not gonna be much difference in flavor and moisture level of the meat.

Not that it really matters, as "steaming and rubbing with fat" sounds a lot less fun than slow boiled in it's own fat, so even if it works perfectly well, I'd have little interest in doing it. And if I'd do confit, I'd definitely want to age it for a while, which you can't do with the steamed and slathered piece.

Anybody want to do a side by side? Would be interesting to read about, though not interesting enough to do it myself :raz:
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#15 tomdarch

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Posted 23 November 2009 - 04:01 PM

I wonder if "steaming" in the words of the NYT writer simply means normal kitchen steaming. I wouldn't be surprised if this was "steaming" with some pressure variation to control the temperature - I'm specifically thinking low pressure to bring the temp down - essentially bagless sous vide. Oh, duh - that's cvap cooking, which Myhrvold and his team mentioned in their presentation. I'm betting that the NYT writer/editor didn't want to delve into the process of explaining the cvap oven.

#16 nathanm

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Posted 14 December 2009 - 08:11 PM

The NYT piece only covered this briefly. Here is a better discussion of the issue.

Most chefs believe that cooking meat at moderately low temperature (typically 160-180F)submerged in fat - called confit - produces a special flavor and texture profile to the meat.

The classic dish is duck leg confit, which was traditionally used to store duck legs - the legs would be salted, then cooked in fat, and after cooking the fat allowed to congeal around the meat which would tend to isolate the meat from air and help it keep longer.

Sous vide confit puts some fat in the bag with the meat, and that seems to work very well. I experimented a bit with that (see the sous vide thread, and a thread on duck confit). Sous vide confit is a lot less messy than a big pot of fat, and requires less fat - like a teaspoon full per bag rathre than a pot full.

But I wondered if there was really anything to this. I didn't believe that the interior of the meat could actually be affected by being cooked submerged in fat. Fat molecules are way too large to penetrate into the meat.

Some people say all sorts of weird things about how confit might work, like the fat forces juices to stay in the meat, but those are like stories of searing meat to "lock in the juices" which have been shown to be wrong.

So, we cooked both duck legs, and pork shoulder several ways. Traditional confit style, sous vide confit (with fat in bag), sous vide (without fat in bag), and low temperature steaming (in combi-oven or CVAP, at typical confit temperatures). Cooking times and temperatures were the same between all of the tests.

It is easy to see/taste if there is some oil/fat on the meat so after cooking we added some oil or fat to the meat that wasn't cooked confit style.

We had one person handle the cooking and plating, and then we did careful taste tests. None of us (trained chefs and sophisticated eaters) could tell which sample was which better than random.

Our conclusion is that there is no human perceptable difference in cooking via confit. Yes, this flies in the face of tradition, but LOTS of traditional "knowledge" turns out to be wrong when examined in detail.

Some people will have a hard time accepting this. My answer is simple - TRY IT. If have not tried it in a controlled, disciplined and fair way, then there isn't much point in arguing about it, because this is not a matter of opinion or faith - it is a simple experiment.

Edited by nathanm, 14 December 2009 - 08:12 PM.

Nathan

#17 Kent Wang

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Posted 14 December 2009 - 09:06 PM

Thanks for weighing in, Nathan.

What temperature did you do the confit? Baldwin recommends "176°F (80°C) water bath for 8 to 12 hours".

Could I achieve the aging effect with sous vide and just a bit of fat? I would assume so. My only worry is the duck jelly (congealed juices) that would normally fall to the bottom of the jar of fat would instead be distributed along with the fat. Would that jelly increase the chance of it becoming rancid?

#18 slkinsey

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Posted 15 December 2009 - 07:55 AM

There is somewhat lengthy discussion elsewhere in these forums about the differences between aged SV confit and aged traditional confit. The general concensus was that SV confit does not particularly "age" -- or at least not the same way that traditional confit does. I think it was Paula Wolfert who said that she thought the distinctive flavor of aged traditional confit came from a minor amount of controlled rancidity.

Rancidity, by the way, is something that happens to fat. So the presence of jelly in the bag should not lead to increased chances of rancidity. The fact that SV confit is cooked and stored in a bag with almost all of the gas removed makes oxidative rancidity unlikely, and the fact that the food is cooked well past the time/temperature for Pasteurization and is stored at low temperature makes microbial rancidity also unlikely. Hydrolytic rancidity (the third cause of rancidity) does involve water, but mostly happens in dairy products and typically requires enzymes and/or bacteria that are killed or unactivated by the extended cooking.

This is not to say that spoilage is not a potential variable -- just that rancidity isn't likely to be the kind of spoilage.
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#19 paulraphael

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Posted 15 December 2009 - 09:48 AM

I've always assumed that the unique flavors of a traditional confit (the slight rancidity, and possibly other aged flavors) are the product of storing, not cooking. Confit was traditionally a preservation method; you'd eat your duck legs weeks after cooking. So it would make sense that you wouldn't taste differences in these methods right after cooking.

#20 Chris Hennes

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Posted 16 December 2009 - 10:52 AM

So all that would be required to replicate the flavor of traditional confit is then to cook the protein sous vide to the appropriate temperature, then cover with fat and let it age for some length of time? No need to even include fat in the SV bag, right, since it doesn't get absorbed and apparently doesn't affect the flavor through any other sort of alchemy?

nathanm, you say "Fat molecules are way too large to penetrate into the meat": can you quantify this? How large are the fat molecules compared to the "meat pore size" (or whichever term is appropriate here)?

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#21 David A. Goldfarb

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Posted 16 December 2009 - 11:05 AM

I also wonder about the "penetration" issue. I assume fat is unable to penetrate the cells of the meat, but if it can ooze into the fibers of the cooked meat, that's not a bad thing to have happen.

In any case, it doesn't sound like there's any particular advantage to the sous vide method, except that it doesn't require as much fat initially. I say "initially," because the fat from confit can be reused for more confit or for other things, if it hasn't gone bad.

#22 OliverB

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Posted 16 December 2009 - 12:51 PM

I don't have the measurements of molecules, but I've read in several places that it can't penetrate meat. That doesn't mean that it won't penetrate the little nooks and crannies all over, especially in cooked meat, which tends to loosen up and open "doors" for anything. But it won't penetrate the meat itself, just the little openings that might develop. As far as I know, you could put meat in any kind of fat for a long time and nothing would happen. Even regular marinades only get into the meat on the surface, contrary to brining, which works because of osmosis and the natural law of things in one container trying to even out. The salt in the brine will first suck water out of the meat, eventually it'll get pulled back in, carrying salt and other flavorings with it, thus making the meat moist and tasty. I guess one could try an experiment, marinade half of one very thick steak in oil and flavorings, the other in brine with the same flavorings. Cook it and then taste compare the inner parts only?

As for duck confit, I would not call the aging controlled rancidity, rancid fat (and only oils/fats get rancid) is unpleasant. The meat ages in the fat. Could be interesting to cook one duck leg as regular confit, steam an other and put in fat after cooking. Let both age the same amount of time and see how things taste. Maybe even steam a third one and then vac pack it and wet age it, I'd guess the effect would be the same. All 3 are cooked, all 3 are sealed away from air and external moisture, while internal moisture is trapped.

I won't do it, if I'd want to make confit I'd go the traditional way, I like doing things that way (which is why sou vide - while interesting - won't be happening in my kitchen anytime soon. Too many other kitchen gadgets and equipments I'd rather buy first.

All just guesswork on my side, I've never done confit and find duck way too expensive to experiment with, but if one has easy access to relatively cheap ducks, could be fun to try.
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#23 Mallet

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Posted 16 December 2009 - 01:22 PM

So all that would be required to replicate the flavor of traditional confit is then to cook the protein sous vide to the appropriate temperature, then cover with fat and let it age for some length of time? No need to even include fat in the SV bag, right, since it doesn't get absorbed and apparently doesn't affect the flavor through any other sort of alchemy?


Probably, but then you would run into some safety concerns. One option might be to do SV confit, then give the finished confit a 15-20 min treatment in a pressure cooker to destroy botulism spores? You might then be able to age in the fridge or in another cool place to your heart's content.

Would FoodSaver bags survive the treatment? To what temperature are they rated?
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#24 slkinsey

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Posted 16 December 2009 - 01:35 PM

The other issue with this idea is that confit isn't strictly speaking a "cook to temperature"
food where all you have to do is get it to equilibrate at the target temperature and then you're done. It is a "time at temperarture" food. Meaning that you want to cook confit at, say, 80C for 8 to 12 hours to get the traditional texture, etc. If you are not planning on storing it in the bag and are planning on storing it traditionally under fat, there is no reason to use SV at all.


It is also relevant what you mean by "traditional confit characteristics." The vast majority of duck leg confit served around the world is not aged under fat, but is simply simmered under fat and stored for at best a brief period of time. I am no expert, but have to believe that less than, say, 10% of confit consumed, even in France, is of the "long aged" variety.
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#25 Chris Hennes

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Posted 16 December 2009 - 01:47 PM

I guess when I hear "80C for 8 to 12 hours" my mind automatically goes to SV because then it's simply matter of setting the circulator and coming back tomorrow: it seems to me that's the simplest way to achieve the desired effect. And I'm sure you're right about the aging: in particular, I don't think that I have personally ever had a confit aged more than a week or so, and only that one because I made it myself. But Wolfert suggests in her book and here on the forums that a pleasant flavor shift occurs if you age the confit, so by "traditional" I basically meant "the Wolfert Way™". I'd love to know what chemical process occurs in the confit over that aging process. The theory seems to be that it depends on a small amount of oxygen permeating the fat layer, which is why aging in the SV bag doesn't yield the same result. Not that I have tested that on my own... has anyone?

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#26 slkinsey

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Posted 16 December 2009 - 01:51 PM

"80c for 8-12 hours" can translate just as easily to "light simmer in the oven for 6-8 hours." It's not the long cooking that makes confit a PITA.
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#27 nathanm

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Posted 16 December 2009 - 08:31 PM

Thanks for weighing in, Nathan.

What temperature did you do the confit? Baldwin recommends "176°F (80°C) water bath for 8 to 12 hours".

Could I achieve the aging effect with sous vide and just a bit of fat? I would assume so. My only worry is the duck jelly (congealed juices) that would normally fall to the bottom of the jar of fat would instead be distributed along with the fat. Would that jelly increase the chance of it becoming rancid?

The time-temperature trade offs are many. In general to get similar results to traditional confit you should do 70C to 80C for 8-12 hours. Note that there is a lot of range there, but there is a large range in what people is "correct" so ultimately it is up to you.

The jelly separates out in the bag, just as in the jar.
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#28 nathanm

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Posted 16 December 2009 - 08:45 PM

The key issue with this whole topic is that it is about an experimental result, rather than opinion.

It seems irresistable for people to theorize about it. One chef told me "I don't agree with this" so I said "why, have you tried it?". He was puzzled - he thought that it was something you should take as an article of faith, or that his training and experinence should dictate the answer even though he had NOT tried it.

A lot of the discussion about SV confit versus traditional has this character - people want to rally around the traditional method, as an article of faith or ideology. The fact is that unless you do a careful, blind taste test under controlled circumstances it is very easy to have an opinion that has no basis in fact.

The issue with traditional vs SV is complicated by the fact that the traditional often has poor temperature control. When we do traditional SV for comparisons we control the temp and time to make it the same. But if you don't do this and use whatever temp your oven produces, it may be different for that reason.

It is possible that some confit has some degree of rancidity/aging, but frankly virturally no confit that is served in a restaurant is aged for very long.

Our experiments show pretty clearly that none of us (including trained chefs and serious eaters) could tell "true" confit from SV, or from non-confit (low temp steamed, SV without oil) when done under controlled conditions. This includes having time and temp be the same, and brushing the non-confit with oil/fat because you can tell that.

So if you don't "agree" fine, it's your perogative to believe what you want to believe. However, I urge you to try the experiment.
Nathan

#29 slkinsey

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Posted 17 December 2009 - 06:29 AM

This all makes sense to me.

One question, and it's more to the underlying chemistry than the experimental results, so it doesn't speak directly to your experiments: I understand that fat molecules are too large to penetrate the meat. What about aromatic molecules? One of the things about your tests is that you were comparing things that all fundamentally would taste like duck with duck fat, and of course duck legs already taste like duck fat to a certain extent. What about duck with some other strongly flavored fat? For example, if one were to compare a duck leg (1) traditionally confited in strong-flavored bacon fat versus (2) SV confited with strong-flavored bacon fat versus (3) steamed and brushed with strong-flavored bacon fat -- would we expect them to taste any different? To what extent would the transfer of bacon aromatics transfer from the fat to the duck? Or are they at this point bound in the fat somehow and won't transfer out of the bacon fat except into a stronger solvent, and otherwise only go where the bacon fat molecules can go?
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#30 Mallet

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Posted 17 December 2009 - 06:33 AM

For now, I'm willing to take it on faith that you've carried out the experiment properly :biggrin:. What I'd like to be able to test is the potential difference between aged and non-aged confit. However, to do that I need a way to age confit with relative safety. Can I pressure cook SV confit in the bag to kill botulism spores?
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