nathanm
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Posts posted by nathanm
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There are sous vide bags that can take the heat - they are called retort pouches. They cannot be sealed by a home edge-sealer type vacuum packing machine (i.e. Foodsaver). They require a chamber style machine.
One could seal them without a vacuum with an impulse sealer - that would work fine.
Alternatively, you can cook things sous vide in a masor jar.
Basically what you are proposing is canned duck confit. It would certainly work.
You could can after sous vide cooking, but once you pressure cook long enough for sterilization, it is unclear you would need any further cooking time. The pressure cooker will, by itself, cook the meat. I am not sure what the texture will be like - I haven't tried this.
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What you call "maturing" the duck confit is aging it.
Yes, it does change the taste, mainly by making the fat slightly rancid, although there are other chemical reaction occuring too.
In a sous vide bag this is not going to happen (or extremely slowly), so if you really want that taste you can cut the bag open and let the cooked confit sit in the fridge for some period of time (days to weeks).
I don't find that this greatly improves the taste. It's basically making the fat go rancid.
Years ago duck confit was made for its preservation aspect, so it was always old and was partly rancid. As a result it was quite salty. Today's duck confit recipes have less salt than the did back in the day, so they are really made to eat fresh without much aging.
You can get the same effect by aging some of the fat prior to cooking it, in which case, yes, you don't need to age it with the meat.
But I think that duck confit is great to eat when cooked fresh, with fresh fat. It's only if you are addicted to the old-time partly rancid taste that you would miss it. Most people these days have never had that.
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The issue with meat tenderizing is much more complicated than you are suggesting. It is not just collagenases that are present, there are also various enzymes - calpains and cathepsins - that degrade proteins other than collagen, as well as some that act on collagen. Meat toughness is largely about collagen, but not exclusively.
It is a very complicated system, and most explanations of it are highly simplified. In part this is because it has not been figured out yet. A lot of recent meat science research has been about using molecular biology tools to study things that were oversimplified in research done in the 1970s.
The key thing is that the rates of enzymatic reactions are greatest above the animal's original body temperature (37C/100F). The higher the temperature, the faster the reaction (dramatically faster, they are exponential in tempertaure), until you get to a point where the enzyme itself is destroyed by the heat. Between 40C and likely about 50C there are some important enzymes active that cause tenderization. They quit at various tempertaures depending on the enzyme.
Conversely, at low temperatures some of these reactions do occur and likely are the cause of tenderization by meat aging. However instead of taking hours they take weeks (21 - 45 days are typical meat aging times).
The trouble with directly interpreting the Laakonen et al result is that their heating ramp, coupled with the thermal gradient in the meat (which depends on the thickness of the meat) means that different parts of the meat would be at different temperatures. So, while they report that tenderization occurred between 50C and 60C, the question is what part of the meat was at those temperatures?
Besides enzymes, there is also thermal conversion of collagen into gelatin. Note that "gelatinization" or variations on that word are not really the correct term. It is generally called denaturing, or hydrolysis, but there is no single accepted term.
This likely starts at 37C (studies differ on this), but at such a slow rate that it is hard to measure. Various scientific studies, particulary those from the years back, say that this process "starts" at various tempertaures, but that is almost surely wrong. This is particularly true of meat science studies done long ago which used ridiculously high temperatures, and in general oversimplified things.
Empirically, the fact is that by 52C the conversion to gelatin is certainly occuring, and for food safety reasons most long time sous vide occurs at 55C/130F, where it is happening. The rate is much slower at those tempertaures than higher (again, exponential in temperature) which is why you typically have very long cooking times.
Bottom line is this:
- Holding meat at 40C-50C (specifically we find pretty good results at 45C/113F) for up to 4 hours is within food safety guidelines, and has a significant tenderizing effect.
- Cooking meat at 55C/130F for at least 8 hours (and often 24, 48 or even up to 100 hours, depending on the cut) also has a significant tenderizing effect.
For really tough meat, you can do both. This works best if you have two water baths and switch the meat from one to the other, or if you have a programmable water bath and set a timer to change the temperature.
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The book is mentioned in Saveur magazine this month, page 44. They actually gave us spot #41 in their "Saveur 100" list.
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Nathan, I recall that one of the controversies of the book is the statement that steamed duck brushed with duck fat tastes the same as duck confit. People didn't believe this, but blind tasting showed that they couldn't tell which was which.
Many people also say that duck confit "matures" and improves over time by being stored in the duck fat. Do you think this is true?
Yes, what you say above is covered in the book. We did blind tastings and could not tell the difference between confit cooked in a steam over or sous vide without fat, then had fat put on at the end. The temperature you cook at and the time matter, but whether it is immersed in oil during cooking does not matter.
Duck confit is a cured meat product that was originally done for preservation - you salt the duck to cure it, then cook it, then (traditionally) you store it in a cool place in the congealed fat which was a sort of oxygen barrier, a bit like sous vide packaging.
During that storage, the fat will oxidize a bit (i.e. get slightly rancid), which you definitely can taste. However you can achieve that by putting aged fat on the meat.
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Fermat's last recipe! A great idea...
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We do have a very good macaron recipe, but it is not in the book, unfortunately.
We want to do a pastry book, but we need to catch our breath after this one.
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Planking is usually done by putting food on a wood plank which is then hit with enough heat (from broiler or otherwise) to cause the wood to burn or smolder, putting a light smoke flavor on the food. Cedar is often used as the wood - see this site or here.
Besides being a cooking technique a large part of the appeal is the dramatic presentation of food at the table on a smoking charred plank of wood.
We don't cover it in detail, but do have one recipe done this way, a cheese course from Seattle chef Scott Carsberg.
Plank cooking wouldn't work in a steam oven - it's about smoke flavor.
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We are not doing a traditional book tour, however we will be doing talking to the press, and probably having some events on the east coast in late march. I suspect that I will do events in Seattle, and a few other cities as well. This is all being planned at the moment so I don't have anything to announce.
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As none of the usual suspects has answered, I'll offer the shrimp formula I was given by a modernist chef: 2 hours at 123°F/50.5°C. For service, he grilled them for 30 seconds per side, but said that was just to warm them up. 50°C seems low to me, but I have to say the shrimp were perfect.
THe prefered time and temperature will depend a lot on the specific shrimp you use. My favorite for most really high quality shrimp is 45C/113F for just long enough to cook through - which is typically 20 min for spot prawns. The 2 hour recipe above sounds a bit long to me.
Note that this is NOT pasteurizing combination, so you should use maximum hygiene and treat as you would for sushi.
To pasteurize, 55C/130F for ~2 hours should work fine, or 30 min at 60C with (to my taste) some loss of quality on the texture.
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Monday we will be posting a recipe for turkey wings to the Modernist Cuisine blog for turkey wings cooked sous vide - you cure them with salt first (as for duck confit) then you cook them 12 hours at 58C/137F for 12 hours.
It's up. Nathan, why 58C for the wings? I'm doing legs and thighs with duck fat SV and keep seeing temps up near 80C. Is the latter more confit and the former less so?
It's the temperature we prefered after doing tests.
The temperature and time you use depends on the result you want. If you want to mimic conventional duck confit then 80C/176F for 8-12 hours is pretty much comparable to most traditional recipes - same temp, same time, and pretty much the same result.
Or you can go to lower temperature. In this case we wanted low temp but we wanted some tenderization, and the combination of 58C for 12 hours was our preference.
Turkey thighs can be done in a similar manner. Every temperature and time will give a somewhat different result.
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Has anyone done the retrograde starch mashed potatoes sous vide? I've always just done them with a pot and a thermometer, but it would be simpler to bag a bunch of potato slices and do them in the waterbath (at least the first cook, but probably both).
Do you think there would be an issue with them being bagged vs. in the water? Is that a good or bad thing?
As others have noted, it works well. We have recipes for potato puree in the book that use this approach.
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Thanks for the detailed reply nathanm -this is exactly what I was looking for!
I had thought that by curing the trout first it would significantly improve the safety issue. Quite sobering to read your response on this...
I will definitely take your advice from this point and cook to order. It seems a few more trials are in order; will also try at 38C.
You're also correct re the temperature of the fish but it is served as a cold starter. It was only meant to bring the fish to room temperature.
Thanks again.
Curing isn't enough by itself, especially at the level of curing salts you are using. Again, you could do it without incident for a while, but if you got some contamination in the system (including cross contamination from something else), then it would be problematic.
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We're serving an Atlantic Ocean Trout at the moment and I want to be sure that it is as safe as possible...
Upon arrival the trout is cleaned, then cured with citrus, herbs, salt, sugar, and honey for 3hrs. Next it is portioned and cooked sous-vide in clarified butter @45C for 25min. We use a chamber type professional vacuum pac machine and a Polyscience 7306. Calibration is routinely checked with infrared and digital stick type thermometers. The trout is immediately chilled in an 80% ice bath, then is held on ice for a maximum of 48hrs. Any unsold pcs are discarded. For service, they are re-heated in a 45C bath for 5min and served. The portions are generally 15-20mm thick, around 50g. Guests are advised that the trout is served mi-cuit; not for pregnant ladies or immune compromised individuals.
Cheers.
Food safety is a statistical phenomenon - if food is very contaminated you can get sick even if you follow the guidelines; if it is not contaminated with pathogens then you can get away with a lot. That is, until you find some contamination.
Personally, I would not recomend the process you are using - I don't use cook-chill sous vide unless you cook to sterization/pasteurization temperatures and times. I would NOT recommend doing cook-chill at 45C. There are many pathogens that can survive that temperature, and then they will continue to slowly grow in the refer for up to 48 hours. This is not a good idea. Yes, you can get away with it if you fish isn't contaminated, but if you encounter some Listeria (or many other pathogens) your approach is not good.
Instead what I would do is just cook the fish at 45C and serve immediately. That is actually much safer than what you are doing. The 45C cooking period will not kill most pathogens, but it will accelerate their growth. Food safety wise you are better off storing the trout raw and cooking it to order than sous vide cooking first and chilling because your first cooking is NOT sufficient to kill many important pathogens.
In my own personal preference I think 45C is fully done fish with respect to texture and taste, not mi-cuit. If I really wanted mi-cuit, that is more like 38C - at that temperature salmon won't change color, and most white fleshed fish won't become opaque. However, the aspect of warning people on the menu is always a good idea.
One odd thing in your description is that you cook the fish for 25 minutes the first time, then reheat for 5 mintues. Are you serving it cold? In general for fish you do not need to cook it by holding it at a temperature - you only cook it long enough reach the desired core temperature. For fish pieces the size you describe 25 minutes should do that. In general for tender food cooked sous vide the reheat time is the same as the cooking time. Obivously that is not true for tough meats cooked for hours or days, but in general reheating takes the same amount of time as the cooking step. The 5 minute reheat won't possibly be enough to reheat the fish all the way through, so my conclusion is that you are serving it cold.
So, my recommendation is to cook to order. You can leave the fish in the bath at 45C during service (for up to 2-3 hours), but then discard what is left afterwards.
As I said in starting this point, it is always statistical so I don't doubt that you have gotten away with the approach you are using now for a while. The trouble is, you don't know that will always be the case, and your current process could make things worse when and if you do have some contamination.
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Monday we will be posting a recipe for turkey wings to the Modernist Cuisine blog for turkey wings cooked sous vide - you cure them with salt first (as for duck confit) then you cook them 12 hours at 58C/137F for 12 hours.
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Yes the original poster is following the thread sporadically. I have made a BBQ map for my upcoming book Modernist Cuisine. The point of the map isn't as a travel guide, it is about tracing the cultural history and complexity of barbeque thorugout the South.
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Here are some replies or comments on recent posts.
The "siphon" in the instant hollandaise recipe is a cream whipping siphon, such as ISI or Liss. A soda siphon won't work. The point of this recipe is that you can make a hollandaise foam that is foamed to order. You can of course just make the hollandaise in a blender.
I prefer pork ribs at 60C/140F for 48 hours, but everybody has their own notion of what "ideal" means.
Duck fat is great stuff - you can render your own, or buy it. However, there is really not much point in cooking with large amounts of it. Just a small amount puts the flavor in. You can even cook without out (sous vide in a bag with no oil) then dress with some duck fat at the end. The turkey thighs (from the Voltaggio video) will come out the same either way - it is not necessary to have a lot of duck fat.
The point of the duck fat is flavor at the end of the cooking process - that's all. Chicken fat would also be good tasting - but a very different taste. Frankly if you are looking for flavorful fat, cook the thighs/legs sous vide then dress with rendered bacon fat at the end.
Reheating something cooked sous vide, then chilled is best done using sous vide again. That avoids overcooking. You can then sear at the very end, or in the case of a fryer, fry at the end. The warm oven suggestion will also work, but harder to control.
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I agree that the key to sous vide is achieving things not possible other ways. Pressure cooking is indeed faster if you don't mind what it does to the meat (grayness etc). Once you go to 70C or above that is pretty much a moot point so pressure cooking is a viable alternative.
Also, there is no one right answer. Short ribs can be good over a wide range of temps and times - you get VERY different results, but depending on what you are looking for it, any of them could be "ideal".
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Dan,
thanks for doing all the tests!
Trying 68°C will be a valuable service to the community to verify the theoretical expectation that above 60°C there should be no collagenase activity and below 70°C there should be poor/slow collagen melting. I never did something of which I expected a poor outcome. Thanks again!
The situation is nowhere near that clear.
First, there are many enzymes that affect tenderness. Some of those enzymes denature (and thus stop working) at various temperatures between 40C/104F and 70C/158F. However there do not seem to be any sharp cut offs.
Degrading collagen by enzymes is one of things that occurs, but the primary collagen effect is due to heat and water alone. Collagen does not "melt" in the usual meaning of the term. Instead it undergoes a process which has many names (hydrolysis, denaturation, gelatinization...) when heated with water, which converts it into gelatin.
This process starts at very low temperatures. Exactly how low is a subject of a lot of debate in the scientific literature. It likely starts just above normal animal body temperature, but the rate is very low. Most chemical reaction rates vary exponentially with temperature, so as the temperature gets low the rate becomes so slow that you must be very patient.
Many food science books make ridiculously wrong statements, saying that collagen does not undergo hydrolysis below 60C/140F. That can trivially be shown to be false by sous vide cooking at 55C/130F. You need to do it for a long time (24 to 72 hours), but it surely works, as people on this threat all know.
The 60C/140F number comes from a 1971 scientific paper, which just wasn't patient enough at the low end of the temperature scale. More recent work on collagen has shown that the effect starts at 50C/122F but likely goes even below that (but at a very slow rate).
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The way to do vacuum reduction is to use a lab vacuum pump that can take moisture, a vacuum filter flask and a hot plate.
The cheapest vacuum pump is a water driven aspirator - they are about $25, but they waste a lot of water.
A motorized aspirator is basically an aspirator connected in a tank so there is no water waste. There are also vacuum pumps made to use with rotary evaporators, which will work but are more expensive.
The vacuum pumps used for vacuum packing are in general not a good idea because they can't take having oil or acetic acid vapor go in the pump.
You also need a vacuum filter flask, in pyrex, a stopper, some vacuum tubing and a hot plate. It helps to have a laboratory hot plate with magnetic stir bar so you can stir the liquid being evaporated.
An aspirator or motorized aspirator will draw a good enough vacuum to boil water well below room temperature - indeed you can chill water with a good vacuum pump. This will work for any type of reduction, whether it is balsamic vinegar or others.
It is great for things like making a reduced strawberry sauce that tastes like raw strawberries rather than cooked.
We have a section in Modernist Cuisine on this, with step-by-step photos, but it is not hard to set up.
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You can do stock via sous vide, but for most meat stocks the low temperature is not an advantage. For fish and shellfish stocks it can be.
We prefer a pressure cooker for making stock from chicken, or mammals (beef, veal, pork).
Using sous vide for reduction is going to be very slow. You are better off boiling and being careful near the end.
The best approach for heat sensitive reduction is vacuum reduction, which is discussed in my book. It's pretty simple once you have a little bit of equipment. You can reduce liquids at refriderator temperatures.
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The book and the team will be featured in a segment on the Martha Stewart show on November 3. It airs on the Hallmark channel in the US. This link announces it.
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The Modernist Cuisine cookbook team will be featured on the Martha Stewart show next week (November 3).
This link has some information and a picture.
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Thanks for the spirited defense that some of you have mounted on my behalf. For some reason the eGullet notification service stopped sending me email, and I have been so busy on the book that I didn't notice until now.
The team has worked hard to earn the trust (at least most of you) have placed in us. I think that you'll pleased when you see the final product.
Here are a few statistics that may help. We have more than 1500 recipes in the book. Many of these we developed, but we also had contributions from 72 chefs around the world, including Ferran Adria, Heston Blumenthal, Grant Achatz, Wylie Dusfrense and David Chang. We also have some recipes based on original creations by people like Thomas Keller, Daniel Boulud, Eric Ripert and many others.
Sous Vide: Recipes, Techniques & Equipment, 2011
in Cooking
Posted
We cover a lot of this in the meat chapter in Modernist Cuisine (it is about 200 pages long). However even there we have to simplify a bit, and much of the details are not known yet to science.
Unfortunately, I don't have the most recent references handy at the moment...will dig them up.