DouglasBaldwin

Phaz, Preparing duck breasts confit-style is the problem. Such tender cuts as poultry (chicken, turkey, duck, goose, etc.) breasts are best prepared as you would tender pork or beef. I cook migratory-bird (duck, goose, etc.) breasts at 135F (57C) until pasteurized (see other posts); I cook non-migratory-birds (chicken, turkey, etc.) at 140F (60C) until pasteurized (see other posts and my guide). I only braise or confit tough cuts of poultry---such as legs and thighs. I hope that answers your question.

Guy MovingOn, The difference is in the context: Mr Goussalt is concerned with industrial sous vide cooking and we are interested in home and restaurant sous vide cooking. If you're trying to cool thousands of pounds (kilograms) of food, successively cooler baths makes a lot of sense. At our scale, it's much easier for us to drop the cooked food into an ice bath until the core's cold enough. That multi-stage cooling improves juiciness hasn't been shown to my satisfaction. First, I'd only consider it when doing braises (i.e., at 70C/160F and higher). In the small scale experiment I did for myself a couple years ago, there was a small difference but it was within my expected error. I've never gotten around to doing a larger scale experiment to see if there is a statistically significant difference. Personally, I usually let my braised pork sit on the counter for about 15 minutes before placing them in my ice bath --- but this is mainly to cool the pouches enough so they're not painful to handle. Edit: Typo

The safety issue is largely the spores as they are much harder to deactivate than the bacteria. I would stick to Doug Baldwin's recommendations. e_monster is correct. The spores of Clostridium perfringens will easily survive your 80C (175F) for 18 hours. Rapid cooling (in ice water) is the best way to prevent sporulation of C. perfringens.

I know a lot of people on this thread don't agree with me, but I like to pasteurize all my fish and shellfish. I do this by cutting the fish into individual portions and cooking them in a 140F (60C) water bath for 40--50 minutes. I use 140F (60C) because the fish becomes mushy at lower temperatures (since it takes much longer to pasteurize) and dry at higher temperatures (since the muscle fibers contract and squeeze out the water held between them). I find that 140F (60C) for 40--50 minutes gives safe, moist, and flaky fish. If you buy sashimi-grade fish, you can heat the fish for 15--20 minutes in a 108F (42C) water bath for rare or a 122F (50C) water bath for medium-rare. I say "heat" because you cannot pasteurize fish at these temperatures. I'm not saying that rare and medium-rare salmon isn't delicious---because it is---but if I'm buying sashimi-grade fish, I'd prefer to eat it as sashimi.

PedroG, I haven't tried 55C/6hrs, I was stating a hypothesis; hopefully Guy MovingOn will let me know if my hypothesis was correct. I haven't had chicken at 57.5C/3hrs for several years; I remember enjoying it but my family being turned off by its appearance. While I almost always use my chamber vacuum sealer, I usually seal the breasts while they are frozen --- since they are frozen, even pulling the highest vacuum doesn't damage their texture.

I'll be surprised if either of you like it. At 55C (131F), the enzyme collagenase will break down a significant amount of collagen in the 6 hours it takes to pasteurize it. You may enjoy chicken breasts at 57.5C (135F) since it only needs 2.5--3 hours. [i remember liking it at 57.5C (135F) when I tried them a couple years ago. My family just couldn't get used to its appearance. Until most people accept that you can't judge safety by appearance, many people will feel uncomfortable eating medium-rare poultry :-(.]

PedroG: That is a wonderfully illustrative picture. Guy MovingOn: When doing confits you have to ask yourself if you are doing it for taste or for preservation. The recipe in my guide is confit-for-taste and uses a lower concentration of salt. Confit-for-preservation uses a larger amount of salt (or salt and sugar) to reduce the water activity* of the meat to below 0.91. This can be done either by packing the meat in salt or using a very concentrated brine---depending on the thickness of the meat, it may take several days (or weeks) to reduce the water activity enough. (See the charcuterie index for more details.) I find confit-for-preservation to be too salty for my palate and just freeze the confit-for-taste I make to keep it safe. (See the food safety section of my guide for more details.) * Water activity (aw) is the vapor pressure of the food divided by the vapor pressure of water at that temperature. A long time ago, food scientists noticed that bacteria stop growing below certainly water activity levels; for instance, C. botulinum cannot grow if aw < 0.94 and Salmonella spp. for aw < 0.92.

You can pasteurize poultry at 54.5C (130F) and 57.5C (135F), it just takes longer: Reducing Listeria by 1 million to 1 in poultry 130F (54.5C) water bath ; 135F (57.5C) water bath mm; hours; inches; hours; mm; hours; inches; hours 5; 5.6; 0.25; 5.6; 5; 1.7; 0.25; 1.7 10; 5.7; 0.5 ; 5.8; 10; 1.8; 0.5 ; 1.8 15; 5.9; 0.75; 5.9; 15; 1.9; 0.75; 2.0 20; 6.0; 1 ; 6.2; 20; 2.1; 1 ; 2.4 25; 6.2; 1.25; 6.7; 25; 2.3; 1.25; 2.8 30; 6.6; 1.5 ; 7.2; 30; 2.6; 1.5 ; 3.2 35; 6.9; 1.75; 7.7; 35; 3.0; 1.75; 3.8 40; 7.3; 2 ; 8.3; 40; 3.4; 2 ; 4.4 45; 7.7; 2.25; 9.0; 45; 3.8; 2.25; 5.1 50; 8.2; 2.5 ; 9.8; 50; 4.3; 2.5 ; 5.8 Here I used D60C5.66C = 5.94 minutes for Listeria monocytogenes, a thermal diffusivity of 1.08 10-7 m2/s for poultry, and assumed the slowest heating shape (an infinite slab) at each thickness. Brining is always an interesting subject. For the last couple of years, I've only been brining meat that I cook well done: pork shoulder for pulled pork; duck and turkey legs for confits; brisket for corned beef; etc. I brine meat I'm going to cook well done to compensate for some of the water that is lost when the muscle fibers shrink longitudinally and squeeze out the water held between its thick (myosin) and thin (actin) muscle fibers. At least for pork, a brine of 7--10% NaCl gives the highest increase in water. But there is another reason to brine: coagulate the albumin before it can coagulate on the surface. This is often called salting out the proteins. This is why Mr Keller sometimes brines fish in a 10% brine for a short time. Edit: Clarified.

Guy MovingOn: When cooking meat, there really isn't any reason to go higher than 80C (175F). Back in the day I did a double-blind taste test between brined (7% NaCl soln for 48 hr) pork shoulder at 80C (175F) for 10 hours and at 70C (160F) for 24 hours: no one was able to tell the difference. Now, cooking vegetables at 80C (175F) may pose some problems. With (non-starchy) vegetables it is all about dissolving enough of the cementing material that holds the cells together to make them easy to bite. [The literature refers to this as the beta-eliminative degradation (or depolymerization) of pectic polysaccharides.] I usually dissolving these pectic substances at 85C (185F) --- others cook their vegetables at 83C (182F). You can cook starchy vegetables though, since most starches gelatinize by 80C (175F) --- I usually cook them for about twice as long at 80C (175F) as I would have boiled them.

That's interesting, I'll look into it and get back to you. I've never tried rapid aging, but I believe PedroG does it frequently. (My beef is dry-aged 28 days, so it doesn't need additional aging.) A low pH marinade just needs to keep any surface pathogens from multiplying---cooking and searing the beef will destroy them later. E. coli stops growing at a pH of 4.0 and I don't know of any food pathogens that can grow at a pH less than that. Some spoilage and beneficial microorganisms can grow at much lower pHs though---such as lactic acid bacteria and some yeasts and molds. [pH isn't the whole story though: weak acids and strong acids affect pathogens in different ways. Weak acids are able to go through the cell membranes of the pathogens and lower its cytoplasmic pH; strong acids can't go through the cell membranes and mainly work by stopping the enzymes on cell's surface. As always, food science is never as simple as it seems.]

Welcome Guy MovingOn, e_monster is absolutely right: Heston's team assumed that the interior of the intact muscle is essential sterile and that searing the outside is sufficient to make it safe. (The big problem now, is that many processors are mechanically tenderizing their primal beef cuts and are not currently required by the government to label them as such. This is a big problem that a lot of people in the food safety community are angry about. Several people have already gotten sick from eating steaks that they grilled because they didn't know the steaks had been mechanically tenderized. So unless you know your meat hasn't been mechanically tenderized, you should assume it has and pasteurize it.) As to why Heston is holding the meat at 50C/122F for 24 hours, let me quote an email I sent to PedroG almost a year ago:

Sorry for not being clearer. I was trying to explain that rendering the fat is not just about melting the fat, but that the connective tissue must also be broken down.

I didn't understand things as clearly back then. The problem is that the fat is deposited in the connective tissue. So the fat is trapped until the connect tissue has been dissolved. This is why RoyK found that his 72-hour brisket at 135F "rendered the fat wonderfully." In confit-style preparations, we dissolve almost all the collagen into gelatin and this allows the melted fat to lubricate the muscle fibers.

Pedro's posted covered things fairly well. I am working on a new plain English sous vide food safety section, and I should have it done in a week or two. Food Pathogens verse Spoilage and Beneficial Microorganisms Food pathogens are separate from both spoilage and beneficial microorganisms. So food pathogens cannot be seen, smelt, or tasted. Food is safe and can be pasteurized at above 126.1°F (52.3°C), the temperate that Clostridium perfringens stops growing. Pasteurization means reducing active bacteria to a safe level and depends on both time and temperature. Pasteurization takes much longer at lower temperatures than at higher temperatures. We are mainly concerned with reducing Escherichia coli, Listeria monocytogenes, and Salmonella spp. to a safe level. Since Listeria is the most heat resistant active bacteria, reducing it by 1,000,000:1 will ensure that E. coli and Salmonella have also been reduced to a safe level. See my guide for time and temperature recommendations. After cooking, the food must either be eaten immediately or rapidly chilled (in an ice water bath) to prevent spores from becoming active, multiplying, and producing toxins. Spores are made by some food pathogens and are very difficult to kill: spores are like seeds and are not dangerous unless they become active during cooling or storage. After rapidly cooling, the food must be kept cold to prevent any active pathogens (which were not killed during cooking or which outgrew from spores) from multiplying. Listeria is able to grow in the refrigerate at above 29.3°F (–1.5°C). If cooking eliminated all the Listeria, we only have to worry about spores becoming active. We worry about three spore forming pathogens: Clostridium botulinum, Clostridium perfringens, and Bacillus cereus. There are two types of Clostridium botulinum: one that likes higher temperatures and one that likes colder temperatures. The colder variety can grow at above 36.5°F (2.5°C) and the warmer at over 50°F (10°C). If cooking kills all the colder variety or they weren't ever in the food, then Bacillus cereus becomes our main concern. Bacillus cereus can grow at above 39°F (4°C). Since almost no home refrigerators spend all their time below these temperatures, I recommend freezing anything cooked sous vide unless it will be used within a few days. Some spoilage and beneficial microorganisms can grow above 126.1°F (52.3°C) or below 29.3°F (–1.5°C). These microorganisms very rarely affect the taste of food cooked sous vide, especially if the food is within its `sell-by' or `use-by' date and doesn't have a strong odor. While searing meat before cooking sous vide will kill the surface microorganisms, it is usually done to develop meaty, savory, and roasted flavors (via the browning or Maillard reaction). If the natural enzymes are not destroyed during cooking (which is common in sous vide cooking below about 140°F/60°C), then they may be active at refrigerator (or even freezer) temperatures and change the taste and texture of the food. [Edit: Fixed typo.]

The Iwatani blowtorch is in a completely different class from those gourmet shop creme brulee torches. The Iwatani blowtorch is at least as powerful as the best plumbing propane hardware torch, but in a more compact and kitchen friendly form. I still love mine and use it several times a week.

I really like my Iwatani butane kitchen blowtorch; it works just as well at searing the meat as the plumbing torches I used to use, but without leaving an off-flavor. Thinking of off-flavors, Dave over at Cooking Issues posted that you can eliminate the off-flavor when searing with a propane blowtorch by using it through a wire chinois. I mainly use my blowtorch for searing beef, lamb and venison. I prefer to use a heavy skillet with just smoking vegetable oil when searing poultry and pork. On my portable (commercial) induction burner with a stainless steal skillet (with a thick aluminum clad bottom) over the highest available heat, it takes me 20--30 seconds to sear each side (of pork and poultry) to a deep golden brown.

From a food safety perspective, I would recommend against opening the pouch and possibly recontaminating the food. Another concern when opening the pouch is warmed-over-flavor (oxidative rancidity)---one study found that foods cooked sous vide are more susceptible to warmed-over-flavor after they are removed from their pouches than traditionally cooked foods. While it is true that the neurotoxin produced by C. botulinum can be destroyed by heating the coldest part of the food to 185°F (85°C) for at least 5 minutes, other (less deadly) toxins (produced by spore forming pathogens) are not destroyed by heating. Since one study found that less than 2% of household refrigerators spend all their time below 41°F (5°C), I generally recommend either storing your rapidly chilled pouches of sous vide cooked for a few days in the refrigerator or freezing them indefinitely.

It depends on two things: how cold is your refrigerator and did cooking reduce non-proteolytic C. botulinum to a safe level? To quote my guide:

Shaun, Using milk is not a problem from the food safety standpoint. Indeed, the `danger zone' for all foods is between 29.3F (-1.5C) [the temperature at which Listeria monocytogenes begins to grow] and 126.1F (52.3C) [the temperature at which Clostridium perfringens stops growing] unless there are additional hurdles which preserve the food between those temperatures. [Note that the danger zone only applied to pathogenic microorganisms, there are spoilage and beneficial microorganisms which can grow at temperatures above and below the danger zone.] Examples of hurdles include canning (which makes the food shelf-stable by reducing the vegetative pathogens and spores to a safe-level and prevents recontamination), decreasing the water activity (e.g., drying meat to make jerky or curing it in salt), decreasing the pH of the food (say by adding acid or through fermentation), etc.* Frequently, several hurdles are combined to allow the food to be stored at temperatures within the danger zone for extended periods of time. * For extremely detailed scientific information on food preservation techniques, I recommend checking out the "Handbook of Food Preservation" edited by M. Shafiur Rahman from your local library system [which can probably get it through inter-library loan from a research university].

Shaun, That is a good question. I have grains on my to-do list, but haven't gotten around to testing them yet. (I tested dried beans last week, and they worked very well.) Since cooking grains is mainly about the gelatinization of the starches granules in the cells, I would first try 175F (80C) (since most starches gelatinize between 140--175F/60--80C). If that temperature is not high enough, I would then try 185F (85C). If neither of those temperatures is high enough, I would try 195F (90C) --- which is what I ended up cooking my dried beans at. As for the cooking time, I would try 1.5 hours at 195F (90C), 2.1 hours at 185F (85C), and 3 hours at 175F (80C) based on the old (very rough) approximation that increasing/decreasing the temperature by 10C halves/doubles the reaction time in biological systems. I would also start with the same liquid-oat ratio you use traditionally, cook it sous vide, and then measure how much liquid you can strain off (and subtract a little less than that amount of liquid on your next experiment). Anyway, that is what I plan to do when I get around to testing the best way to cook grains sous vide. I look forward to hearing about your results. Very Best Wishes, Douglas

Just to be clear, you are either (i) vacuum sealing one thigh per pouch or (ii) vacuuming sealing several thighs in each pouch, but ensuring that they are in a single layer. You are then using the rack in the sous vide supreme (with the slots parallel to the counter) to hold the sealed pouches so they are not touching each other and are completely submerged under the water. And, you only start the cooking time after the water bath has beeped to tell you that the temperature has returned to the set point of 146F (63.5C). Moreover, have you checked the calibration of your water bath by setting it to 100F (37C), waiting 20--30 minutes after it beeps that it has reached the set temperature, and then measuring the temperature of the water with an oral thermometer? All that said, I prefer to my chicken legs (thighs and drumsticks) cooked confit style --- 175F (80C) for 8--10 hours. Also, I typically cook by chicken breasts at 140F (60C) for at least 2 hours. And yes, I was referring to raw garlic cloves. Roasted garlic can be used, but (as mentioned above) is quite mild. Most the time, I do not place anything in the pouch with the protein (meat, poultry, fish) and then just make a flavorful sauce to spoon/pour over the top after I sear the meat or poultry (usually in a smoking hot skillet). If I do use garlic in the pouch, I do exactly as slkinsey said --- I use powdered garlic or garlic which has been cooked in oil until it is golden brown and fragrant.

Jan, Perhaps I should have said, well known in the academic literature and used extensively by industrial food producers. Even in the modern food (or molecular gastronomy) movement, there is still frequently a 10--20 year delay from academic journals to restaurant kitchens. For instance, it is well known in the academic literature (see [Waldron, et al. Trends Food Sci Tech 8 (1997) 213--222]) that you can reduce the extent of softening of some fruits and vegetables when cooking by either increasing the Ca2+ levels or pre-cooking the vegetable at 50--60C before cooking (for say 30--45 minutes); the former (the addition of calcium) I heard used by Dave Arnold and Nils Norén last year to improve the texture of cooked bananas, but I haven't heard the latter being used by anyone yet (despite its obvious applications to carrots in stew). Edit: Fixed typo.

It is well known (see [schellekens, 1996]) that you can cook green vegetables sous vide if you first blanch them. I frequently cook fresh green beans sous vide by (i) blanching them for 10--15 seconds in vigorously boiling water, (ii) shocking them in ice water, (iii) vacuum sealing them with some chopped onions, butter and bacon, and (iv) cooking them in a 185F (85C) water bath for 45--60 minutes. If you want to search the scientific literature on cooking vegetables --- and there is some amazing research out there --- it is frequently described as the beta-eliminative degradation (or depolymerization) of pectic polysaccharides. [Which just means the cementing material (the pectic polysaccharides) that hold the cells together are being weakened by heat.]

I always assume the worst and proceed accordingly. I generally recommend either holding the food at or above 130F (54.5C) until serving or rapidly chilling it in an ice water bath (which is at least half ice) for the time listed in my guide. After rapidly chilling, the food should either be stored in the refrigerator for a few days* or (labeled and) frozen indefinitely. * While foods cooked sous vide can be safely held at below 38F (3.3C) for three to four weeks, one study found that less than 2% of the refrigerators they tested in peoples homes remained below 41F (5C) during the entire monitoring period of their study!

Thanks. I believe my publisher wants to have my book on shelves early next year (2010). If any of you would like to help me field test recipes, just send me an email (see my guide for my email address) with what equipment you have and your current level of sous vide experience.