by Jeff Potter
The problem is that if you’re cooking fish sous vide at only 113°F / 45°C, then you won’t reduce the pathogens to a safe level. So either pasteurize your fish by cooking it at 140°F / 60°C for about 40–50 minutes or make sure that very few pathogens grow and that the fish has a very low amount to begin with by buying from a trusted source.
Can one reduce the level of parasites by freezing?
Parasites, certainly. Though freezing fish at home will affect the quality of fish, because consumer freezers just can’t freeze the fish fast enough to prevent large ice crystals from forming. Now, it’s completely possible that you can buy already frozen, high-quality fish, or simply find out from your fishmonger whether or not it has already been frozen for a sufficient amount of time to kill any parasites.
But freezing won’t kill the different bacterial food pathogens that one might be concerned with, and there’s always the concern of chemical contamination, especially with shellfish that are harvested from questionable waters.
How do you know if something will work when you go to sous vide it?
I never really know, but I like to really scour the research journals for clues to the underlying processes involved. I first look to see if anyone else has already done it. With the wealth of scientific knowledge now available to us through the Internet, it’s very likely that someone has asked and answered a closely related question. Then I just try and adapt it to the home kitchen.
It always surprises me how often I can take things directly from an academic journal and apply them in the kitchen.
Cooking with Sous Vide
While the general principles of sous vide cooking are the same regardless of the food in question, the exact temperatures required to correctly cook and pasteurize it depend upon the specifics of the item at hand. Different meats have different levels of collagen and fats, and denaturation temperatures for proteins such as myosin also differ depending upon the environment that the animal came from. Fish myosin, for example, begins to denature as low as 104°F / 40°C, while mammalian myosin needs to get up to 122°F / 50°C. (Good thing, too, otherwise hot tubs would be torture for us.)
Because meats can be grouped into general categories, we’ll cover them in broad categories. We’ll look at beef and other red meats together, for example, but keep in mind that variations between different red meats will mean that very slight changes in cooking temperature can yield improvements in quality. Data for the graphs in these sections are from Douglas Baldwin’s "A Practical Guide to Sous Vide Cooking"; see the interview with him on the previous page for more information.
Beef and other red meats
There are two types of meats, at least when it comes to cooking: tender cuts and tough cuts. Tender cuts are low in collagen, so they cook quickly to an enjoyable texture; tough cuts require long cooking times for the collagen to dissolve. You can use sous vide for both kinds of meat; just be aware of which type of meat you’re working with.
Time at temperature chart for beef and other red meats.
Beef Steak Tips
One of the primary benefits of sous vide is the ability to cook a piece of meat, center-to-edge, to a uniform level of doneness. Beef steak tips are a great way to demonstrate this.
Place in a vacuum bag:
1–2 pounds (~1 kg) steak tips, cut into individual serving sizes (7 oz / 200g)
1–2 tablespoons (15–25g) olive oil
Salt and pepper, to taste
Shake to coat all sides of the meat with the olive oil, salt, and pepper. Seal the bag, leaving space between each piece of meat so that the sous vide water bath will make contact on all sides.
Cook in a water bath set to 145°F / 63°C for 45 minutes. Remove bag from water bath, snip open the top, and transfer the steak tips to a preheated hot pan, ideally cast iron. Sear each side of the meat for 10 to 15 seconds. For a better sear, don’t move the meat while cooking each side; instead, drop it on the pan and let it sit while searing.
You can create a quick pan sauce using the liquid generated in the bag during cooking. Transfer the liquid from the bag to a skillet and reduce it. Try adding a dash of red wine or port, a small pat of butter, and a thickening agent such as flour or cornstarch.
Notes
In sous vide applications, it is generally easier to portion out the food into individual serving sizes before cooking. This not only helps transfer heat into the core of the food faster (less distance from center of mass to edge), but it also makes serving easier, as some foods—especially fish—become too delicate to work with after cooking. You can still seal all the pieces in the same bag; just spread them out a bit to allow space between the pieces once the bag is sealed.
I find adding a small amount of olive oil or another liquid helps displace any small air bubbles that would otherwise exist in a dry-packed bag. The quantities of oil and spices are not particularly important, but the direct contact between the spices and food does matter. If you add spices or herbs, make sure that they are uniformly distributed throughout the bag; otherwise, they will impart their flavor only to the pieces of meat they are touching.
Some chemical reactions in cooking are a function of both time and temperature. While myosin and actin proteins denature essentially instantly at sufficient temperatures, other processes, such as collagen denaturation and hydrolysis, take noticeable amounts of time. The rate of reaction increases as temperature goes up, so while collagen begins to break down at around 150°F / 65°C, duck legs and stews are often simmered at or above 170°F / 77°C. Even at this temperature, the collagen still takes a matter of hours to break down.
The drawback to cooking high-collagen meats at this temperature, though, is that actin also denatures. While the fats in high-collagen cuts of meats can mask this, there is still a certain dryness to the finished dish. Since collagen begins to break down at a lower temperature than actin, though, it’s possible to avoid this. The catch is that the rate of reaction is so slow that the cooking time stretches into days. With sous vide, though, this isn’t a problem, if you don’t mind the wait.
48-Hour Brisket
Seal in a vacuum bag:
1–2 pounds (0.5–1 kilo) high-collagen meat, such as brisket, chuck roast, or baby-back pork ribs
2+ tablespoons (30g) sauce, such as barbeque sauce, Worcestershire sauce, or ketchup
½ teaspoon (3g) salt
½ teaspoon (3g) pepper
Cook for 24 to 48 hours at 141°F / 60.5°C. Cut bag open and transfer the meat to a sheet pan or baking dish and broil to develop browning reactions on outside of meat, one to two minutes per side. Transfer liquid from bag to a saucepan and reduce to create a sauce. Try sautéing mushrooms in a pan in a bit of butter until they begin to brown and then adding the sauce to that pan and reducing until the sauce is a thick, almost syrupy liquid.
Notes
If your meat has a side with a layer of fat, score the fat to allow the marinades to contact the muscle tissue underneath. To score a piece of meat, drag a knife through the fat layer, creating a set of parallel lines about 1″ / 2 cm apart, then a second set at an angle to the first set to create a diamond pattern.
For additional flavors, add espresso, tea leaves, or hot peppers into the bag, along with whatever liquid you use. Liquid smoke can give it a smoky flavor as well.
If your sous vide setup does not have a lid, be careful that water evaporation doesn’t cause your unit to burn out or auto–shut off. One technique I’ve seen is to cover the surface of the water with ping-pong balls (they float); aluminum foil stretched over the top works as well.
Fish and other seafood
Fish cooked sous vide is amazingly tender, moist, and succulent. Unlike fish that has been sautéed or grilled—cooking methods that can lead to a dry and rough texture—sous vide fish can have an almost buttery, melt-in-your-mouth quality. Other seafoods, such as squid, also respond well to sous vide cooking, although the temperatures do vary.
Time at temperature chart for fish and seaf
ood.
Note
If you are going to be using sous vide cooking in any professional setting, I highly recommend consulting Chef Joan Roca’s book Sous Vide Cuisine (Montagud Editores).
Cooking fish sous vide is so straightforward that you don’t need a recipe to understand the concept. The following tips should help in your experimentation with sous vide fish:
Fish cooked to a doneness level of medium rare (131°F / 55°C) or more undergoes pasteurization by being held at temperature for a sufficient length of time (see the time-for-thickness graphs provided for lean and fatty fish).
Lean fish, such as sole, halibut, tilapia, striped bass, and most freshwater fish, require less time to cook and pasteurize than fattier fishes, such as arctic char, tuna, and salmon.
For fish cooked to a doneness level of only rare (i.e., cooked in a water bath set to 117°F / 47°C), pasteurization is not possible. Thus, if you are poaching salmon at 117°F / 47°C, be mindful that it will not actually get hot enough to kill all types of bacteria commonly implicated in foodborne illnesses. (Salmonella, fortunately, is not prevalent in fish.) Cooking fish at 117°F / 47°C for less than two hours presents no worse an outcome than eating the fish raw, so the usual recommendations for fish intended to be served raw or undercooked apply: buy sashimi-grade, previously frozen fish to eliminate parasites (see How to Prevent Foodborne Illness Caused by Parasites in Chapter 4), and don’t serve the fish to at-risk individuals.
Note
The FDA’s 2005 Food Code excludes certain species of tuna and "aquacultured" (read: farm-raised) fish from this requirement, depending upon the farming conditions (see FDA Food Code 2005 Section 3-402.11b).
If your fish comes out with white beads on the surface (coagulated albumin proteins), brine it in a 10% salt solution for 15 minutes before cooking. This will "salt out" the albumin via denaturation.
Sous Vide with Prepackaged Frozen Fish
The grocery stores where I live sell frozen fish in vacuum-packed bags. In some cases, the fish, which has been cut into individual portions, is frozen in marinade, making it the perfect sous vide–ready food: it’s already vacuum-packed; it has been frozen per FDA standards, thus killing common parasites; and it has been handled minimally, having been frozen and sealed shortly after catch, reducing chances of bacterial cross-contamination. The time is ripe for sous vide to catch on big time: the food industry is already selling food in sous vide–ready packaging!
My favorite use of sous vide—well, besides making so many foods just plain delicious and easy to prepare for dinner parties—is using prepackaged frozen fish to make my daily lunch. My routine is fast, easy, cheap, and yummy:
Fill sous vide container (a pasta pot, in my case—I have an industrial circulator) with hot water from the tap. Using hot water means I don’t have to wait for the immersion circulator to heat up the water.
Drop frozen vacuum-packed fish in the water, as-is, straight from the freezer. Because it’s a single portion, the amount of time it’ll take to thaw is relatively short. Just remember: pasteurization times start once the core of the food has reached the target temperature. With a frozen item, you’ll have a hard time knowing when this occurs. I cook a single portion of fish for long enough to ensure that both thawing and pasteurizing have occurred. And because sous vide cooking is forgiving of longer cook times, for most types of fish leaving them in the water bath for an extra half hour won’t affect the quality.
Go for a run. Go to the gym. Do some errands. Write a section in a book about cooking frozen fish in a bag.
Fish out the bag, cut it open, drop the fish on a plate with some steamed veggies and brown rice, and voilà: lunch.
Note
If you’re preparing yourself a meal ahead of time, you can drop the cooked fish into a container with some frozen veggies, which do double duty by acting as ice cubes to rapidly cool the fish down.
The quality of frozen fish can really vary. Frozen salmon from one store can turn out mushy and unappetizing, while the same type of salmon from a different chain can come out moist, succulent, and perfect. This is mostly likely due to differences in freezing techniques: rapid freezing does less damage to the tissues by limiting the amount of time ice crystals have to aggregate and form larger, dagger-like shapes that can pierce cell walls. If you’ve had bad results with frozen fish, blame the freezing technique, not the fact that it has been frozen.
Chicken and other poultry
One of the greatest travesties regularly foisted upon the American dinner plate is overcooked chicken. Properly cooked chicken is succulent, moist, and bursting with flavor—never dry or mealy. True, the potential of contracting salmonellosis from undercooked chicken is real; besides, raw chicken is just gross. But I’m not suggesting undercooking chicken—just cooking it correctly.
The "problem" with cooking chicken "correctly" is that, from a food safety perspective, ensuring pasteurization (sufficient reduction of the bacteria that cause, say, salmonella) requires holding the chicken at a high enough temperature for a sufficiently long period of time. "Instant" pasteurization can be done at 165°F / 74°C, but at this temperature the actin proteins will also denature, giving the chicken that unappealing dry, mealy texture. However, pasteurization can be done at lower temperatures, given longer hold times. Sous vide is, of course, extremely well suited for this: so long as you hold the chicken for the minimum pasteurization time required for the temperature you’re cooking it at, you’re golden. Even if you hold it too long, as long as it’s below the temperature at which actin denatures, the chicken will remain moist. Another win for sous vide!
Time at temperature chart for poultry.
Sous vide chicken breast
As with fish, you don’t need a recipe in the traditional sense to try out sous vide cooking with chicken. Here are some general tips:
Chicken has a mild flavor that is well suited to aromatic herbs. Try adding rosemary, fresh sage leaves, lemon juice and black pepper, or other standard flavors in the bag. Avoid garlic, however, because it tends to impart an unpleasant flavor when cooked at low temperatures. When adding spices, remember that the items in the bag are held tightly against the meat, so herbs will impart flavors primarily in the regions that they touch. I find that finely chopping the herbs or puréeing them with a bit of olive oil works well.
As with other sous vide items, allow space between the individual items in the vacuum bag to ensure more rapid heat transfer, or place individual portions in separate bags.
Slow Cooker Versus Sous Vide
"Wait a sec," you might be thinking, "this ‘sous vide’ thing...how’s it different from a slow cooker?" I thought you’d never ask!
They’re not actually that different. Both hold a reservoir of liquid at a high-enough temperature to cook meat but not boil water. Sous vide cooking has two advantages over traditional slow cooking, though: the ability to dial in a particular temperature, and to minimize the amount of variance that occurs around that temperature.
With a slow cooker, your food cooks somewhere in the range of 170–190°F / 77–88°C. The exact temperature of your food and the extent to which that temperature fluctuates aren’t so important for most slow-cooked dishes. This is because slow cooking is almost always done with meats that are high in collagen, and as discussed in Chapter 4, these types of meat need longer cook times in order for the collagen to denature and hydrolyze and transform into something palatable.
However, this isn’t true for cuts of meat that are low in collagen, such as fish, chicken breast, and lean cuts of meat. For these low-collagen items, cooking needs to denature some proteins (e.g., myosin) while holding other proteins native (e.g., actin). The difference in temperature at which these two reactions occur is only 10°F / 5°C, so precision and accuracy are important. Sous vide wins hands down. It’s not even close.
Try cooking ducks legs both ways. Seal up two legs and cook them sous vide at 170°F / 77°C. Meanwhile, prepare a second set of legs in a slow coo
ker. Cook for at least six hours and then examine the difference.
Sous vide duck legs.
Slow-cooked duck legs.
Vegetables
The geeky way to think about cooking is to consider the addition of heat to a system. Adding heat isn’t a spontaneous thing: there will always be a heat gradient, and the difference between the starting and target temperatures of the food will greatly affect both the cooking time and the steepness of the gradient.
This is one reason to let a steak rest at room temperature for 30 minutes before grilling: 30 minutes is short enough that bacterial concerns are not much of an issue, but long enough to lower the temperature difference between raw and cooked steak by a third. You can use a water bath to the same effect for vegetables: reduce the heat delta by holding them in a moderate-heat water bath (say, 140°F / 60°C) for 15 to 20 minutes, and then steam or sauté them.
Note
Yes, you can cook vegetables sous vide, too, but because vegetables don’t begin to cook until relatively high temperatures—typically above 185°F / 85°C—and even then take a while, it’s easier to cook them with traditional techniques.
