nathanm

Cryovac is a brand name of vacuum packing equipment (http://www.cryovac.com/). Most of their products are geared toward large scale industrial food packaging. The "cryo" in the name is meant to imply cold because the first application was vacuum packing fresh meat for cold storage. However, you might think that cryo implies frozen or cryogenic - but that is not the case, the bulk of Cryovac's market is fresh rather than frozen. It's a brand name; it does not have to be technically correct. Virtually all meat in the US, and a lot in Europe, is vacuum packed like this at some stage between slaughter and the final market. Cryovac packaging is usually done in heat shrink bags (also called thermo-retractable bags). You seal in a vacuum chamber, then dunk into 200F boiling water (very briefly) to shrink the bag. In case you care, here is background on vacuum packing in the meat industry http://meat.tamu.edu/packaging.html Within the meat industry, Cryovac is a leading packaging supplier and pioneered the whole field, so most professional meat people will use the term "cryovac" as the generic name for every vacuum packing system (like people use Kleenex for all kinds of facial tissue). Sous vide is about cooking in a vacuum packed bag. As such it uses a similar vacuum packaging machine. Typically you use different bags (sous vide requires a bag that can take heat) and usually you don't use heat shrink bags in SV (although there are some applications). The recent Amanda Hesser article used the term "cryovacking" in the context of sous vide which I guess some people use, but it is technically incorrect and misleading because the meat packing industry already uses the term to mean vacuum packaging without cooking. I think this usage happens because chefs are familiar with the term cryovac from talking to their meat supplier. They even refer to the vacuum packing machine as a "cryovac machine". However, the Cryovac company does not even make the small packaging machines - they are made by Koch Equipment http://www.kochequipment.com/overview/ and distributed by Cryovac (among others). These are sturdy machines, and you find them in some restaurant kitchens. However, they are not as sophisticated as the better European machines that are microprocessor controlled. I agree that it is confusing and inappropriate to confuse vacuum packing for shipment and cold storage with sous vide which is vacuum packing for cooking. The Cryovac company does NOT promote sous vide cooking at all - if you search their web site there are ZERO mentions of the term. Some of their big industrial systems will package then cook the product in the package, but that is nothing like real sous vide. So, anyway there is more than you (probably) wanted to know about the relationship between sous vide and cryovac.

This is very interesting. I'm going to try some experiments here also. You could call this "hot aging" of the meat. I have tacitly relied on this in the past via slow normal cooking but haven't tried explicitly holding the meat at low temperatures deliberately. The thing with confit texture is that it is produced by much higher temperatures and you are just not going to get it any other way. I make confit at 170F to 180F - it just does not have the confit texture otherwise. However, sous vide texture is very good - you just have to consider it a new option rather than a way to achieve an old traditional effect.

Industrial heat guns are basically overpowered electric hair dryers. They pour out hot air at between 90F to 1200F depending on the model. They are used for things like stripping paint off wood, and other times you want very hot air, without having a flame. I've used them for cooking applications, and I am sure that other people have too. I think that it would interesting to compare notes on what they are useful for in the kitchen. Blowtorches are obviously similar, but they are much hotter (3000F typically) and this poses some problems that heat guns solve.

the clips are a great idea!!

this is not surprising. 141f is low and at this temp it will never be "falling off the bone". it will get very tender, but it will be more like fillet mignon tender than the falling off tender that is typical of meat braised at high temperature. i have cooked tough beef cuts up to 80 hours. eventually you get a mushy sort of tenderness which is not that appealing, but it never gets the way that hot braised meat gets. the whole issue is whether you want this effect or not. in some cuts it is nearly miraculous - you get medium rare looking meat which has a unique texture that is tender in the sense that you can easily eat it, but it does not fall apart quite like a hot braise would. note that being "done" is entirely subjective here. you can control very precisely the effect you want to have by choosing the cut of meat, the time and the temp. if you want a typical hot braise texture you need some heat - less than for conventional, but you need the heat to get that texture. alternatively you can get the medium rare effect, which can be amazingly good, but it is not the familiar braise effect. the ideal cut for long time low temp sv is one that is tough, but does not have huge amounts of collagen or fat. so, shin / ossobuco / hocks of veal, lamb or other red meats do not do well (my opinion) this way and are better with higher heat. brisket, short ribs, paleron (aka flat iron steak) work very well. fillet mignon, rack of lamb, or other tender cuts get more tender if held at 130f to 140f for a while, but you need to be careful or you can make them a little mushy. vegetables are another matter entirely. they need to be cooked fairly hot in order to break down the celluose and other material in cell walls. no amount of time at 141f will do very much for veges. you typically need to be at least 180f and more like 190f to do the cell wall restructing that we expect to soften vegetables. delicate fruits - like berries - are different of course - there you want to avoid the cellular breakdown so low temps work much better.

If you are serving immediately you do not need to cool it down - just serve it. Resting time serves several purposes. One is to normalize temperature. As you can see from the temp / time tables if the bath temp is close to the final temp you don't need to do this at all because the meat is already equilibrated. Resting is far more important when the cooking temperature is much higher than final temperture, as it is with normal roasting or grilling. Resting is very important there. It is also important to a lesser degree for SV where the cooking temp is significantly higher than final core temp. The problem with waiting until 5 degrees lower than max is that the meat will get quite cold, especially with things you are not cooking to very high temp to begin with. During the rest time the muscle fibers may relax and other processes will proceed. However, juice will not get sucked back into the meat. The gentle cooking you typically do in SV generally does not need resting for this reason.

This would work. Seasoning would not be there, but that is not the end of the world. I don't think you could reseal the cryovac bag

Yes, something in the bag helps. However for your really long times, some juice will come out no matter what (your 18 hour short ribs, for example). Extended cooknig times break collagen into gelatin - the lower the temperature the It is not true that you need to keep the temperature above 140F that is a myth promoted by simplified food safety guidelines. The myth is easily disproven if you look at the actual data - see the posts above with the FDA documents. The FDA approves as low as 130F for a variety of red meats, and as low as 136F for poultry. The caveat is that you must keep them at those temperature for at least a certain amonut of time.

This is the standard gospel that most people talk about with food safety. It is not really correct, but it is the simplified version that most people quote. Keeping your food less than 4 hours in the "TDZ" is good practice as a broad rule, but the specifics depend on the situation involved. As an example, it depends on the kind of food, the pH and several other factors like whether there is an anerobic environment (no oxygen) and how long it will be stored later (even in a fridge). In posts above this is discussed in more detail, or you can go to the real food safety data and find out. If you are going to do leave in the bag for an extended period then this is NOT enough because it won't kill botulism spores. Actually most bacteria die above 120F, but some need to 125F. Death is statistical and the number of bacteria killed depend on the time at the temperature. The rate is exponential in temperature above a certain point, so that they amount of time you need decreases dramatically as temperature increases. The FDA documents that I posted previously show the amount of time you need.

115F to 117F is in the range were you may want to cook fish, but not other things, and you don't want to cook the fish for hours anyway (would not be safe). So it sounds like you could use your slow cooker to do that. Typically the food in sous vide pouches is put in cold, but you absolutely have to have to cold ahead of putting in the bath - again for food safety you don't want it lying around for a long time. The water temperature does drop when you put cold product in. How much depends on the volume of the water versus product. Your slow cooker may not put out enough energy in warm mode to reheat the water when you put fish in. No real way to find out without testing it. For short cooknig times, as you typically would have for fish, many chefs just use a stove and watch the temperature. It is not as convienent as an automatic water bath but it does work. As the cooking time grows longer this gets more impractical, but for short times it works fine.

I posted a bunch of cooking time tables in the sous vide thread. That includes a table that is how I would cook beef fillet. The key variable is how thick it is.

Laboratory water baths circulate the water with a pump - that keeps temperature more even. It is possible to cook this way in still water also, just don't pack it too full so that water can circulate (via convection).

The NYT Magazine article can be found here (requires free registration). The story is titled "under pressure" which is a bit odd since pressure is not really part of the process. Many people think that the contents of the vacuum bag are under pressure. That is not so - they are at standard atmospheric pressure. Indeed, everything around us is subject to atmospheric pressure - normally we don't notice because it is unform in all directions. Being squeezed at 14.7 lbs per square inch is not a problem if it is uniformly squeezed in all directions. In a sous vide bag, there is no air inside the bag, so the bag is stuck to the food with atmospheric pressure. For meat, fish or similar products they basically are at atmospheric pressure, with the bag stuck to them. If you try to pull the bag away from the food you will be fighting atmospheric pressure of 14.7 lbs per square inch. Porous items - like a sponge - have empty pocket normally filled by air. In a sous vide bag there is no air, so the pockets are filled with a vacuum. Now the atmosphere pressure is not uniform - there will be pressure on teh outside of the bag, but not on the inside. For a weak porous material, it could be crushed because the material is not strong enough to support the vacuum inside. In the case of a stronger porous material, such as a bag of peanuts, there are air pockets in between the peanuts. In a sous vide pouch they will not be crushed but will seem to be welded together as a result. However, it is important to realize that the food is not actually under any more pressure than it is normally. Indeed, the crushing occurs only because some parts are under less pressure than normal. There are situations where food really is under pressure, such as in a pressure cooker (which typically operates up to twice atmospheric pressure), or in presses that squeeze juice from grapes etc. There are also vacuum marinators / tumblers which hold the food at less than atmospheric pressure for a long time. But in sous vide pouches the food is NOT under pressure. Anyway, the article mainly focusses on a broad description of sous vide. It winds up mixing several different things - vacuum packing for food storage, vacuum packing to crush porous items (they mention watermelon), sous vide cooking for cook-and-hold and finally mentions sous vide used for immediate service in restaurants. The hero of the story is Bruno Goussault, who is credited as being the originator of sous vide. It also mentions George Pralus who is more often credited with orginating sous vide in France. As Paula's post shows there is actually a long history of cooking in vacuum sealed pouches, but the article does not focus on that history other than Goussalt / Pralus. A few of the things in the article are a bit strange, or incorrect. It quotes Goussault as saying that 52C/125F is hot enough to kill bacteria. Most authorities (including FDA) would say you need to be higher to 54.4C/130F, and even then you need to leave it there for a LONG time - it is not just about temperature. However, as explained in previous posts, that really only applies to cook-and-hold sous vide - for immediate service you don't need to be at that limit at all so long as the total time spent above refridgerator temperature is kept to under 2 hours. It goes on to say that chefs from Citronelle and French Laundry prefer to cook salmon to 47C, which Goussault claims is unsafe compared to 50C. Well, my recommendation is 45C - just don't do cook-and-hold. Goussalt also is quoted recommending brining salmon prior to sous vide cooking - 10 minutes in a 10 percent salt solution for 10 minutes. This is supposed to prevent the albumen in the salmon from leaking out. This article is testimony to the growing popularity of sous vide, and its higher visibility. Then again, as Paula's post shows there have been sporadic thrusts in the past, so this is not the first time it has occurred.

SV produces a result much like poaching. Anything that you would be happy to serve poached can be served as-is out of the SV bag. So, as an example poached chicken, fish, lobster could be done SV. However, some products are unusual to serve poached (steak), or even if it is possible to serve it in the style of somethnig poached you may not want to. So, a lot of people want to finish the SV product after taking it out of the bag to simulate another cooking method. There are two choices - you can hide it, or you can sear it. Hide it means cover the product with a sauce or other coating. You could, for example, pop the SV product in batter and deep fry it - that is an extreme form of hiding it. A post earlier in the thread shows applying a crumb coating to rack of lamb, which is a great example. Another sort of coating would be a "lacquer" type sauce coating - say a reduction of soy sauce, honey and balsamic vinegar, or something else which is opaque and will stick to the meat. Heston Blumenthal serves a SV salmon dish at the Fat Duck where the salmon is enveloped in an agar-agar gel coating prior to cooking (I think). Since agar will hold to 140F and he is not cooking the salmon above that, the gelled coating sticks. This is another form of hiding, and of course contributes flavor too. Searing is the other approach, in which you want to create the Malliard reaction and brown the exterior. The trick here is to use very high heat because the food is already cooked through and you just want to change the surface without deeply heating the product, and thus overcooking it. Here are some approaches I use: - Pan sear - the pan has to be very hot and the oil smoking. - Blowtorch - this is my favorite SV finishing approach. This is particularly effective for poultry, but it works for most things - even steak. It is the perfect way to crisp the skin on whole squab cooked SV, for example. - Salamander / broiler. Like the blowtorch, only you generally have less control, however it is also less labor intensive because you don't have to play the torch across the food. - Grill - particularly if you want grill marks. The grill must be set much hotter than you would use to actually cook because you want to achieve good grill marks in much less time than you would for raw meat where you want to cook the interior. Some people like to do this BEFORE you do the SV cooking. This can work but it has a problem which is that the browned exterior crust gets soggy during the SV cooking. So I generally do the finishing step later. The people who like browning it first say that the Malliard reaction products - the flavors of browning - will soak into the meat and help flavor it. This is possibly true, but I have not noticed that this effect is important enough to make up for the soggy crust effect. If I want the browned flavor I take a dark brown stock or demi-glace and put some of that into the bag. I usually only sear the top of the food, or the top and the sides. Nobody seems to turn their steak over and examine the bottom Note finally that you can enhance the browning effect by adding a coating to the meat which will caramelize. A marinade or brine for poultry that includes sugar will greatly increase the skin's tedency to brown. THe same thing is true for meats - at least when you can accept a sweet sauce. Lamb, pork and many other meats are often served with sweet, (or sweet and spicy) sauces. So, either marinate or cook in the bag with something like sweer, or dip the product in a thin sauce or glaze prior to browning. Obviously, this would mean you have to watch to make sure you don't burn the glaze/sauce. That is almost a hybrid between hiding and searing.

Sounds like you are having fun. One minor quibble - fat in the bag isn't going to help keep juices in because its density is actually lower than the juices. You can see this because if you pour off the juices and fat, (or stock and fat etc.) fat floats to the surface. Its density is lighter than water, or meat juices.

Yes, I have tried brisket and it comes out very good, although not with the barbeque flavor. One could do a two stage process to get that. Joan Roca makes "smoked" fish by taking a smoke infused oil, and the cooking things in it sous vide. He does this with fish primarily. Might work with something else. The canning question is more complicated. For short duration, in the presence of oxygen there is no problem. As one example, there are two ways to pasteurize milk - HTST (high temperature, short time) and LTLT (low temperature low time). LTLT is generally defined as 30 minutes at 143F/61.7C. It is an approved method for dairy product pasteurization. The primary caveat is that canning must be able to kill botulism spores. The botulism organism Clostridium botulinum dies easily - it is not hard to kill. The spores are more resilient however. In food served immediately, the spores are not a problem - they are not harmful to eat, and the organism cannot grow in the presence of oxygen which is surely present during service and consumption. However, in canning, or in cook and hold SV, there is the potential opportunity for the spores to grow and produce the bacterium, which then produces the toxin which is what makes you sick or kills you. It is the long term storage, without oxygen, that makes canned food susceptible - basically the bacterium dies during sterilization / pasteurization, but the spores can survive and grow if the are in an anoxic situation. As a secondary issue, canning generally seeks to achieve a 10D to 12D reduction in bacterial population - that is a 10 to the 12th reduction. FDA food safety is generally 6.5D to 7D, and many experts concede that 5D is enough. So, the times would wind up being longer even besides the spore issue. Those are the primary differences between canning and food safety for immediate service. You also ask what the difference is between meat and fruit - the main issue there is pH, some bugs live in specific pH ranges. You can kill them outright with the right pH and not need heat at all, or more generally pH changes the time you need to kill the spores. Acidic foods are in general much lower risk. There are also some proteins present in beef and other meats that can allow botulism spores to survive even in low pH. So to be really certain you need to have empirical data relevant to the conditions under which you are operating. An alternative approach is to sterilize the food a second time after canning. The botulism toxin is destroyed by heat - 10 minutes at 170F is supposed to be enough. So, cooked food that is meant to be cooked to that level. Here is some background on botulism: http://edis.ifas.ufl.edu/FS104 Here is a very good explanation of the math behind the thermal death curves for botulism, and how it applies. http://www.nzifst.org.nz/unitoperations/ht....htm#thermdeath Using this approach you could design a process for canning. However to be sure you have to look at the factors like pH, and other things that may affect survival. If you look hard enough on the web you may find somebody has done this already. Two final warnings here, which contradict one another. First, you take your life in your hands when you cook, at all, and especially so with home canning. You need to be careful before you adopt a new approach to make sure that it is really going to work and not make you sick or kill you or your guests. Second, because of this dire risk, most of the information you find on the topic is wildly exaggerated. People tend to "round up" the actual amount of time by adding one safety factor after another with the result that the actual consumer level advice is not really to be trusted - it has been exaggerated "for your own good" to a point that is often excessive and wildly out of keeping with the actual science. Last year there were 169 cases of botulism in the US, some from wounds and other sources, and very few of them fatal. Meanwhile about 40,000 people die from car accidents. If the same worry were applied to cars we would be told not to drive over 10 MPH. That might actually be good for us, but I don't anybody would be accept it. So, the lesson of these two is that you have to be informed by the best science and then you need to take the level of risk you feel comfortable with. Also, remember that ANY food safety guideline can be undone by a stupid mistake like dirty fingernails or other poor hygiene practices.

vacuum sealing a liquid depends on your vacuum machine. On consumer level machines that do edge sealing (like FoodSavr), liquid can be a mess. One techique to control that is to freeze the liguid into ice cubes first, then it seals just fine. Professional chamber style machines can take liquid directly. However, if you put too much in, or are not careful, you can still make a mess. The liquid will boil when the vacuum hits its peak and that can cause it to boil over. So, you have to be careful to not put too much in the bag, and then watch it to shut the vacuum off if it starts to boil over. In fact, I store all of the stock I make in vacuum bags.

The collagen to gelatine transformation is the main thing you are trying to achieve by cooking for a long period of time. However, there are lots of other proteins that are reacting and eventually these reactions will have an affect on the meat. If you are going to cook for a long time - say 24 hours - then you want a cut with a lot of collagen to begin with. The same is true if you cook at higher temperatures. If you want to make confit - duck confit, pork, lamb, carnitas whatever - then I cook at higher temperature, because the goal is to achieve a particular effect. I generally cook those at 80C/176F for 8 to 12 hours. This is similar to the conventional cooking process for them because you are trying to achieve a similar affect. You could cook duck legs for 24 hours (or there abouts - I have only done a couple expermients so far) at low temperature say 54.4C to 58C and get a good result. It would taste good, but it would not be at all similar to traditional duck confit. But that sort of confit treatment will destroy a tender cut. I do a lamb confit based on lamb shanks cooked SV with oil in the bag for 8 hours at 80C/176F. The collagen in the shank turns to gelatin and the result is great. Put a lamb tenderloin through that and you'd get something terrible. We have not mentioned what you put in the bag with the meat. That can also break down the meat proteins, so you have to be very careful, particularly for the long cooking times.

Originally, the primary use of SV was about storage of the food after cooking and before service - cook and hold SV. In that version they used much higher temperatures due to food safety concerns. More recently immediate service of SV has become the main use - at least in high end restaurants. The idea of cooking in a bath at 55C to get a 54.4C result is pretty recent. Tender cuts of meat don't need the long treatment, and in fact will eventually become mushy as you suggest. If 58C is your preference, fine, but remember that with sufficient time you can tenderize other cuts. Brisket, for example, does not need to go to 72C/165F. I have cooked tender brisket at 54.4C/130F - it just takes 36 hours, whereas the reaction is much faster at 72C - a few hours will do. I am not sure what the limit is. The longest I have cooked anything is 72 hours. I did two experiments - flat iron steak (paleron in French) and beef cheeks. I did that at 54.4C/130F and 57.8C/136F. The flat iron steak was great at 36 hours and too soft at 72 hours. The beef cheeks were terrible, they seem to need more temperature or more time. When you say cooking over 18 hours is not to your preference, I'd suggest that you try some meat cooked at a lower temperature. The difference between 54.4C and 58C is striking. It isn't just the time - it is the combination of time and temperature. At low temperature (54.4C) I can show you tough meat that is still way too tough at 18 hours.

This is the time for boneless cuts. Bone conducts heat differently than meat (although not as different as you might think.). I did the calibration tests with very uniform cuts of meat so as to keep everything simple. Bones to one side - like a bone-on rib eye, T-bone, porterhouse are not going to affect the cooking time because the shortest path for heat transmission is not through the bone. The maximum rise after the rest period is the desired temp - i.e. 54.4C/130F in that table, 45C/113F in the fish table. So, if you take out the meat at the point when the core reaches that temp, it will then overshoot to just reach the temp for the table before starting to drop. You are correct that this is the minimum time to reach the core temperature. So, for a tender cut like fillet you are done. For a cut that needs collagen break down you need to then add as much time as is required. I do tough beef for 24 - 36 hours at 54.4C/130F. I have done it all the way up to 72 hours. I'll get around to tabulating some of that eventually.

Here is a little bit more about the big tables for cooking times and temperatures. As explained in a post above, I generally cook at the lowest temperature setting, or perhaps just one above. So, I will cook at 131F / 55C for a 54.4C /130F final core temp. Joan Roca recommends 65C/149F. I don't know why he prefers the higher temperature - it speeds things up, but not enough that it is worth the various negatives. Consider a 1 inch / 25mm thick piece of meat cooked to 54.4C/131F. At 55C it takes 41 minutes. At 65C it takes 17 minutes. Unfortunately if you really want the meat to be within +- 1 degrees C (or 1.8 F) then you must time this to plus or minus 50 seconds otherwise you overcook it. This is not the end of the world, but it is easy to mess up this way. And, if your meat is not exactly 25mm, well that makes a variation too. In the 55C case, you just leave it in a little longer and it can't overcook. Not so with the higher temperature bath. If you want to sterilize it for food safety reasons (which is generally not required for beef steak, at least in the US) then you must use a second bath at 55C becaues it must sit there for an additional 112 minutes (see FDA chart I linked to in a post above) after the core reaches 54.4C/130F. You can't do that with your 65C bath. So, why not cook it at 55C to start with? I will probably write to Roca and ask. Note that the cooking times depends very strongly on temperature and on thickness. Moving the temperature down 10C (65C to 55C) increases the cooking time by almost 3 fold. Double the thickness to 50 mm and the 55C time goes to 2.5 hours, 65C time goes to just over an hour. That is a BIG change. Note that the exact times here are for SV cooking, but the same principle holds for ANY kind of cooking - increasing the thickness, or the temperature differential, radically changes cooking times. In SV we have an option that does not exist in most other kinds of cooking - we can cut the food to portion size prior to cooking. It is easy to do small vacuum bags that have an individual portion in them. In many approaches to meat cookery thick pieces are used primarily to prevent the center from being dried out or overcooked. That is not an issue with SV. One big lesson from the chart is that cutting the food thinner radically reduces cooking time. So, rather than increase heat, I tend to cut the food size. The only reason not to do thin pieces is if the post-SV cooking would be problematic. Many people like to brown or crisp the outside after SV, with a salamander, blow torch, hot pan or other method. A very thin piece of meat is easy to ruin that way. There are also aesthetic and other reasons to have big chunks of food. But the lesson from the tables is that thickness comes a big price.

Moderator's Note: Please click here to see nathanm's table for cooking a wide variety of foods started at 5C/41F.

Moderator's Note: Please click here to see nathanm's fish cooking table.

Glad you like the posts! Yes, you have to be very careful with any kind of cooking. Cook and hold SV has MUCH more concerns associated with it. Sous vide at temperatures above 130F/54.4C can be easily food safe. The only issue, as I discuss above, is that if you have a very large piece of food you could have a cooking time so long that there is a problem. Cooking long enough to sterilize is easy. Cooking fish at 45C/113F is more of an issue - but as long as cooking time is a couple hours or less you are within guidelines. Note that this is only for immediate service not cook and hold.

The times are Hours: Minutes: Seconds I think you may be looking at the second and third lines of the table where the time for 56C is 1 Minute, 19 seconds, and the time for 60C is 53 seconds. Also, note that you need to make sure you are comparing rows which have the same thickness of product. A thicker product takes much more time.