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Confit myth


Kent Wang

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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.

Nathan

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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

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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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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?

Martin Mallet

<i>Poor but not starving student</i>

www.malletoyster.com

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Is a nitrite cure typical for confit? I'd worry about altering the taste too much. Water boils inside a pressure cooker at about 250F. I'm not sure the bag would melt at that range, but I'm a little worried about leaching from the bags.

Martin Mallet

<i>Poor but not starving student</i>

www.malletoyster.com

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Paula Wolfert, who knows a thing or two about confit, says that SV confit does not appear to evolve in flavor from aging. I've had SV confit in my refrigerator for as long as 6 months (my refrigerator hovers just above, and sometimes just below freezing) and could detect no differences between the aged SV confit and unaged SV confit. Apparently, some exposure to air is necessary -- although I should hasten to point out that I don't have any aged traditional confit to compare, so I'm taking it on faith that there is a noticable and beneficial evolution of flavor in aged traditional confit. As Nathan points out, one is extremely unlikely to get aged confit in a restaurant.

As for botulism... while I agree this isn't something one would like to grow, I believe it's true that so long as you cook the meat sufficiently prior to consumption, the toxin is neutralized. Again, an SV pouch would seem like an easy way to do this. Simply toss the unopened bag of aged confit back into a waterbath long enough to neutralize the toxin.

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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?

We didn't try this, but I expect that what would happen is that fat soluable flavors might transfer from the cooking fat to the fat in the meat. But probably not very much.

So if you cook duck legs in bacon fat, there will be some flavor transfer. However, if you steam duck legs and then toss them in bacon fat, you'll get some flavor that way too. If the taste is strong enough (which bacon usually is) I think this they would taste pretty similar.

Nathan

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Can I pressure cook SV confit in the bag to kill botulism spores?

Wouldn't that run the risk of melting the bag? I imagine most vacuum sealer bags aren't intended to go up to temperatures high enough to kill botulism spores.

What about going the nitrite route?

You can get SV bags that will take pressure cooking - they are called "retort pouches".

However, there is another factor - pressure cooking will very change the texture and flavor, much more than aging will. You can experiment with this and see how difference the taste is.

If you want to pressure cook sous vide, conventional Ball / Mason canning jars work very well. By pressure cooking you are basically canning the duck confit.

I am skeptical that SV sealed confit will "age" - my own experience is that it stays the same. Of course part of the point of SV sealing is to prevent oxidiation, so that is quite plausible.

I am also quite skeptical about aging on pressure cooked confit because regardless of whether it is in a retort pouch or a mason jar, it will be sealed, and so very little aging is likely to occur.

Nitrate cure will have a pretty dramatic effect on taste - if you want ham tasting duck confit, then go right ahead, but this is NOT going to taste like non-nitrate duck confit.

Aging in the sense of fat oxidation is another story - that will certainly happen to some degree. Part of the issue with confit was to use the congealed fat to prevent oxidation of the meat itself.

Nathan

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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?

We didn't try this, but I expect that what would happen is that fat soluable flavors might transfer from the cooking fat to the fat in the meat. But probably not very much.

So if you cook duck legs in bacon fat, there will be some flavor transfer. However, if you steam duck legs and then toss them in bacon fat, you'll get some flavor that way too. If the taste is strong enough (which bacon usually is) I think this they would taste pretty similar.

Since you don't have to use much fat to do SV confit, I will probably try this with bacon fat to see what happens. I would assume that doing it SV might also amplify any flavor fransfer from the bacon fat to the duck as it does with herbs, etc.

I was thinking that, if I wanted to see how mucl flavor actually transferred to the duck from the confiting fat, the way to test for that would be to remove the duck leg from the pouch and run hot water over it until all the external fat melted away. At this point, presumably there would be no bacon fat remaining on the duck leg and any difference in flavor would have had to be the result of flavor transfer from the fat. Does that make sense? If so, it should be easy to do some experiments using different aromatic fats (bacon, lamb, etc.), melting off the external fat and tasting for differences.

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I was thinking that, if I wanted to see how mucl flavor actually transferred to the duck from the confiting fat, the way to test for that would be to remove the duck leg from the pouch and run hot water over it until all the external fat melted away. At this point, presumably there would be no bacon fat remaining on the duck leg and any difference in flavor would have had to be the result of flavor transfer from the fat. Does that make sense? If so, it should be easy to do some experiments using different aromatic fats (bacon, lamb, etc.), melting off the external fat and tasting for differences.

Just to be sure, cook one without bacon fat, then annoint with liquid bacon fat for a minute or two, then try to wash it away and use that as a control.

Since it takes soap to wash bacon fat smell off my fingers, I assume that even rinsing it hot water may not be enough.... but the control will tell you.

Nathan

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  • 2 weeks later...

This is somewhat tangential but I noticed that both Keller (in Under Pressure) and Paula Wolfert have noted that if you plan to keep sous vide duck confit more than a week or so that it should be repackaged. I'm not quite sure I understand why keeping it in contact with the "duck jelly" is problematic but I'm obviously quite concerned about botulism.

I have some confit that's about 4 months old, was chilled rapidly after sous vide confit, and has been refrigerated ever since (the bag is still tightly vacuumed). Would people here eat this? Or throw it away?

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  • 2 weeks later...

Nathan - If you have access to an MRI, it might be interesting to see if there is any evident difference in traditional vs SV vs steamed. Sort of like the work Heston did with yogurt marinades.

Exactly what fat are you using to coat the duck after steaming? I only ask because I wonder what effect the long low cooking has on the fat. I may try the experiment of simply holding some rendered duck fat at 70c for 8h and then doing a blind taste test vs duck fat that has been recently rendered and taken to 70c for only a brief period. My guess would be that I would not be able to detect any difference, but its not something I would want to discount.

Also, last time I made confit, there were other guests at the party (spices, ect.), and I'd have to think they would benefit from some extended contact with warm oil as well. This would seem more influential than the means of heat transfer.

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I would be shocked if there was any difference using MRI, but I have not checked. The operative point for cooking is that we could not taste any difference.

For fat we used either neutral oil (canola or similar) or rendered fat (pork or duck). It doesn't really matter as long as you use the same fat for the test. Obviously, one can taste duck fat versus neutral oil, so if you compared traditional confit to meat annointed with neutral oil you can tell a difference. But confit in oil versus annointed with oil has no difference in taste, and ditto for rendered fat.

Fat does oxidize, and that change can be tasted in at least some cases, so there probably is a slight taste difference to oil that has been heated in the open air at 70C for 8 hours, versus one that was brought to temperature quickly. At least some of the "aging" that happens with confit stored after cooking is fat rancidity. It's also one of the reasons that aged beef tastes different - up to a point a little rancidity is helpful.

The main point of our work is that there is nothing special about cooking immersed in oil. Sous vide, or low temperature steaming (in CVAP or combi-oven) is basically identical in terms of what happens to the meat.

Nathan

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For fat we used either neutral oil (canola or similar) or rendered fat (pork or duck). It doesn't really matter as long as you use the same fat for the test. Obviously, one can taste duck fat versus neutral oil, so if you compared traditional confit to meat annointed with neutral oil you can tell a difference. But confit in oil versus annointed with oil has no difference in taste, and ditto for rendered fat.

Are you using pure rendered duck fat or duck fat that's gone through the confiting process? If the former, do you not miss the salty, herbal, meaty notes of the confit fat?

PS: I am a guy.

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Both prerended fat, and fat from confit. The key point here is that cooking in the fat does not matter. Just put the same fat on at the end.

Note that duck legs and thighs still have some fat in them, so any way that you cook them some of that fat will render out and be on the meat. So even if you use a neutral oil to cook confit it will still have some duck fat taste/smell.

Nathan

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  • 3 weeks later...

It appears that the "myth" is rather widespread, even in the sous vide literature. I was looking at Baldwin's recipe for pork shoulder and he recommends adding a bit of lard into the bag. If I understand what Nathan is saying, then one could achieve the same effect by just applying the lard at the end.

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