Cooking For Geeks Part 15

Consumer vacuum food sealers. These devices suck the excess air out of a plastic bag and then seal the bag by means of melting and fusing the opening of the bag. They don't create a true vacuum (in the sense that the food isn't subjected to a reduction in atmospheric pressure), but they do pull out most of the excess air. This is perfect for sous vide, because the function and purpose of the bag is just to allow rapid heat transfer from the water bath to the food via convection currents. Air in the bag would both slow the rate of heat transfer and also cause the bag to float in the water, preventing the face-up side of the bag from absorbing heat. These devices suck the excess air out of a plastic bag and then seal the bag by means of melting and fusing the opening of the bag. They don't create a true vacuum (in the sense that the food isn't subjected to a reduction in atmospheric pressure), but they do pull out most of the excess air. This is perfect for sous vide, because the function and purpose of the bag is just to allow rapid heat transfer from the water bath to the food via convection currents. Air in the bag would both slow the rate of heat transfer and also cause the bag to float in the water, preventing the face-up side of the bag from absorbing heat.

Resealable plastic storage bags. Sealable sandwich and storage bags (e.g., Ziploc bags) are not safe for Sealable sandwich and storage bags (e.g., Ziploc bags) are not safe for boiling boiling food. The concern with boiling applications is the potential for the plastic to leach into the food. The melting point of the type of plastic used in these bags is only a few degrees higher than the boiling point of water. BPA (bisphenol A) contamination would also be of concern, especially if you are adding oils inside the food. Check to make sure the manufacturer of the bags you have does not use BPA. food. The concern with boiling applications is the potential for the plastic to leach into the food. The melting point of the type of plastic used in these bags is only a few degrees higher than the boiling point of water. BPA (bisphenol A) contamination would also be of concern, especially if you are adding oils inside the food. Check to make sure the manufacturer of the bags you have does not use BPA.

NoteSC Johnson, the manufacturer of Ziploc-branded bags, does not use BPA.

Sous vide cooking, however, does not boil the water. 170F / 75C is about the highest temperature you might use in sous vide applications; 140F / 60C is about the warmest that's commonly encountered. Is 170F / 75C safe? SC Johnson is on record claiming that, yes, "[Ziploc] bags can be safely heated to 170 degrees Fahrenheit [76C]."

Remember, the function of the bag is to allow heat to pa.s.s quickly from water to food via convection, so if you do use a plastic bag, make sure to remove as much air as possible. You can submerge most of the bag, leaving just the sealing strip at the top above water, and then seal it. Adding a bit of olive oil or marinade helps, because it'll better conform to the shape of the food.

Douglas Baldwin on Sous Vide[image]Douglas Baldwin is an applied mathematician at the University of Colorado at Boulder who, failing to find a good guide to sous vide, created his own, "A Practical Guide to Sous Vide Cooking," available at http://www.douglasbaldwin.com/sous-vide.htm. He is also the author of He is also the author of Sous Vide for the Home Cook Sous Vide for the Home Cook (Paradox Press) (Paradox Press).How did you hear about sous vide, and how did you get involved in it?I was reading an article in the New York Times New York Times by Harold McGee, and he mentioned sous vide. While I knew quite a bit about cooking, I had never heard the term before and was intrigued. So I did what any good geek does: I went to Google and did some research. There was some information but not enough to meet my curiosity. So I turned to the academic journals and found a wealth of information. by Harold McGee, and he mentioned sous vide. While I knew quite a bit about cooking, I had never heard the term before and was intrigued. So I did what any good geek does: I went to Google and did some research. There was some information but not enough to meet my curiosity. So I turned to the academic journals and found a wealth of information.It took me three or four months to collect and distill the 300 or so journal articles I found and publish the first draft of my guide online. I also did some calculations to figure out how long it takes things to cook and how long it takes to make them safe.Safety is one of the big topics that comes up with sous vide and I'd love to talk about that in a moment. But first, what turned out to matter more than you expected when cooking sous vide?People always worry about the vacuuming process, but that's really the least important part, even though the name sous vide means "under vacuum." It's really the precise temperature control that is important.Long-term precision is important, because you don't want slow drifts when you're cooking for days to cause your meat to be overcooked. But short-term fluctuations in temperature really aren't that important because they will only affect the very outer portion of the meat. As long as the heat is oscillating less than one or two degrees Fahrenheit and the mean temperature is constant, you should be fine.Wow! Cooking meats for days? What sorts of meats actually need cooking for that length of time?Well, my favorite is beef chuck roast cooked for 24 hours at 130F / 54.4C. It's delicious. It transforms one of the least expensive cuts of beef into something that looks and tastes like prime rib.It's all about the conversion of collagen into gelatin. This conversion is pretty rapid at higher temperature, taking only 6 to 12 hours at 175F / 80C to completely convert everything-well, almost everything. But at lower temperatures like 130140F / 54.460C, it can take 24 to 48 hours for the same conversions to occur.When I look at something like brisket being cooked at 130F / 54.4C for 48 hours, alarm bells go off in my head. Isn't there a potential bacterial risk here?Well, certainly there's no risk at 130F / 54.4C. The pathogen that determines the lowest cooking temperature is Clostridium perfringens Clostridium perfringens. Its highest temperature reported in literature is 126.1F / 52.3C. So as long as you're above that temperature, there won't be any food pathogens growing.Now, there is the possibility of spoilage or beneficial microorganisms growing at these lower-cooking temperatures. That's one of the reasons that some people will sear ahead of time or drop the package of vacuum-sealed food in a pot of boiling water for a couple of minutes to kill off any thermophilic microorganisms that might be in there, like lactobacilli. But, in terms of safety, there's no concern whatsoever.How about things like salmon, which are cooked at even lower temperature ranges than 130F / 54.4C?If you would be fine eating the salmon raw, then cooking it for a couple of hours at a very low temperature, say 113F / 45C, isn't going to be a problem. If you wouldn't be comfortable eating it raw, then you probably shouldn't be cooking it at anything less than pasteurization temperatures and times.Most food scientists and food safety experts agree that you should pasteurize fish. Even though it may not taste the same, or possibly quite as good, at least you'll feel a little more safe.Food safety is about controlling both the actual and the perceived risk. Many people perceive the risk of fish to be much less than the risk of pork, but in many ways it's probably the other way around.In our modern agro-industrial complex, we don't really know where things come from. With this decrease in knowledge of where our food came from, what field, how it was processed, and how it finally gets to our table, I tend to take the att.i.tude of "pasteurize everything and hope for the best." Though it may not be what everyone wants or likes to hear.What are the risks and what can somebody in the kitchen do to partially mitigate those risks?When you're trying to deal with food safety, especially when it comes to pathogens, it is about three things. First, starting with a low initial level of contamination, which would mean buying, for example, very good and very fresh fish for which you know the origin. The second is to prevent the increase in the level of contamination and is frequently accomplished with cold temperatures or acids. The third is reducing the level of contamination, usually by cooking.The problem is that if you're cooking fish sous vide at only 113F / 45C, then you won't reduce the pathogens to a safe level. So either pasteurize your fish by cooking it at 140F / 60C for about 4050 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 sh.e.l.lfish 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.[image]

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 104F / 40C, while mammalian myosin needs to get up to 122F / 50C. (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.

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Time at temperature chart for beef and other red meats.

Beef Steak TipsOne 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: - 12 pounds (~1 kg) steak tips, cut into individual serving sizes (7 oz / 200g) - 12 tablespoons (1525g) 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 s.p.a.ce 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 145F / 63C 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 b.u.t.ter, 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 ma.s.s 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 s.p.a.ce 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 quant.i.ties 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 150F / 65C, duck legs and stews are often simmered at or above 170F / 77C. 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 BrisketSeal in a vacuum bag: - 12 pounds (0.51 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 - teaspoon (3g) salt - teaspoon (3g) pepper Cook for 24 to 48 hours at 141F / 60.5C. 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 sauteing mushrooms in a pan in a bit of b.u.t.ter 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 autoshut off. One technique I've seen is to cover the surface of the water with ping-pong b.a.l.l.s (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 sauteed or grilled-cooking methods that can lead to a dry and rough texture-sous vide fish can have an almost b.u.t.tery, melt-in-your-mouth quality. Other seafoods, such as squid, also respond well to sous vide cooking, although the temperatures do vary.

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Time at temperature chart for fish and seafood.

NoteIf 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 Sous Vide Cuisine (Montagud Editores). (Montagud Editores).

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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 (131F / 55C) 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 ba.s.s, 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 117F / 47C), pasteurization is not possible. Thus, if you are poaching salmon at 117F / 47C, 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 117F / 47C for less than two hours presents no worse 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 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 How to Prevent Foodborne Illness Caused by Parasites in in Chapter4 Chapter4), and don't serve the fish to at-risk individuals.NoteThe 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 alb.u.min proteins), brine it in a 10% salt solution for 15 minutes before cooking. This will "salt out" the alb.u.min via denaturation.[image][image]

Sous Vide with Prepackaged Frozen FishThe 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 videready 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 videready packaging![image]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 voila: lunch.NoteIf 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.

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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 165F / 74C, 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!

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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 pureeing them with a bit of olive oil works well.

- As with other sous vide items, allow s.p.a.ce 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 170190F / 7788C. 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 Chapter4 Chapter4, 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 10F / 5C, 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 170F / 77C. Meanwhile, prepare a second set of legs in a slow cooker. Cook for at least six hours and then examine the difference.[image]Sous vide duck legs.[image]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, 140F / 60C) for 15 to 20 minutes, and then steam or saute them.

NoteYes, you can cook vegetables sous vide, too, but because vegetables don't begin to cook until relatively high temperatures-typically above 185F / 85C-and even then take a while, it's easier to cook them with traditional techniques.

I often cook steak tips at the same time that I preheat bok choy, Swiss chard, or other hearty greens, using the same water bath for both the steak and the veggies. This works because the veggies don't actually cook at the temperature that the meat is cooking at.

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This technique works great for small dinner parties. I bag and seal the steak tips just before my guests show up, and once they arrive, I drop the bag of steak tips and some bok choy into a water bath set to 140F / 60C. Thirty minutes or so later-after catching up with my guests, sharing a beer or gla.s.s of wine, and noshing on cheese and bread-I pull the steak tips out and let them rest for a few minutes, during which time I quarter the bok choy and steam it in a hot frying pan.

Because the bok choy is already warm, it reaches a pleasant cooked texture in two to three minutes, at which point I transfer it to the dinner plates. Reusing the same frying pan, I quickly sear the outside of the steak tips, which I then cut and transfer to the plates. Total time spent while guests wait? Five minutes, tops. Number of dirty dishes? One, plus plates. And it's delicious!

Enhancing texture [image]

Ever wonder why some vegetables in canned soups are mushy, textureless blobs, but others aren't? Some vegetables-carrots, beets, but not potatoes-exhibit a rather counterintuitive behavior when precooked at 122F / 50C: they become "heat resistant," so they don't break down as much when subsequently cooked at higher temperatures. Holding a carrot in a water bath at around 120F / 50C for 30 minutes causes enhanced cell-cell adhesion enhanced cell-cell adhesion, science lingo for "the cells stick better to each other," which means that they're less likely to collapse and get mushy when cooked at higher temperatures.

During the precooking stage, calcium ions help form additional "crosslinks" between the walls of adjoining cells, literally adding more structure to the vegetable tissue. Since "mushy" textures occur because of ruptured cells, this additional structure keeps the vegetable tissue firmer by reducing the chance of cellular separation.

The normal solution to mushy vegetables is to refrain from adding them until close to the end of the cooking process. This is why some beef stew recipes call for adding vegetables such as carrots only in the final half-hour of cooking.

For industrial applications (read: canned soups), this isn't always an option. In home cooking, you're unlikely to need this trick, but it's a fun experiment to do. Try holding carrots at 140F / 60C for half an hour and then simmering them in a sauce mixed in with a batch of sliced carrots that hasn't been heat-treated. (You can cut the heat-treated carrots into slightly different shapes-say, slice the carrot in half and then half-rounds, versus full-round slices-if you don't mind your experiment being obvious.) [image]

Chocolate Tempering chocolate-the process of selectively melting and solidifying the various forms of fat crystals in cocoa b.u.t.ter-can be an intimidating and finicky process. The chocolate must first be melted to above 110F / 43C, then cooled to around 82F / 28C, and then heated back up and held between 89F / 31.5C and 91F / 32.5C. Once tempered, you must play a thermal balancing act: too warm, you lose the temper, and too cold, it sets.

It's not exactly correct to describe chocolate as something that "melts," because chocolate is a solid sol, a colloid of two different solids: cocoa powder and cocoa fats. The cocoa powder itself can't melt, but the cocoa fats that surround it can. Cocoa b.u.t.ter contains six different forms of fats, and each form melts at a slightly different temperature.

The six forms of cocoa fat are actually six different crystalline structures of the same type of fat. Once melted, the fat can recrystallize into any of the six forms. It's for this reason that tempering works at all-essentially, tempering is all about coercing the fats to solidify into the desired forms.

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Melting points of the six polymorphs of cocoa fat.

NoteHow do scientists tell when something is melting? Two common techniques are used: differential scanning calorimetry (DSC) and x-ray diffraction. In DSC, energy is added to a closed system at a controlled rate, and the temperature of the system is monitored. DSC picks up phase changes (e.g., solid to liquid) because phase changes require energy without a temperature change. X-ray diffraction looks at how x-rays scatter when pa.s.sed through a sample: with each phase change, the x-ray pattern changes.

It's not a matter of different types of fats; it's the structure that the fat takes upon solidifying that determines its form. Two of these forms (Forms V and VI) link together to create a metastructure that gives chocolate a pleasing smoothness and firm snap when broken. Chocolate with a high number of Form V structures is said to be tempered. tempered. The other primary forms (IIV) lead to a chalky, powdery texture. Form VI occurs in only small quant.i.ties, due to the temperature range at which it crystalizes. Chocolate that has been exposed to extreme temperature swings will slowly convert to Forms IIV. Such chocolate is described as having The other primary forms (IIV) lead to a chalky, powdery texture. Form VI occurs in only small quant.i.ties, due to the temperature range at which it crystalizes. Chocolate that has been exposed to extreme temperature swings will slowly convert to Forms IIV. Such chocolate is described as having bloomed bloomed-the cocoa particles and cocoa fats separate, giving the chocolate both a splotchy appearance and a gritty texture.

To further complicate things, the fats in cocoa b.u.t.ters don't actually melt at an exact temperature, and the composition of the fats varies between batches. The ratio of the different fats determines their exact melting point, and the ratio varies depending upon the growing conditions of the cocoa plant. The fat in chocolate from beans grown at lower elevations, for example, has a slightly higher melting point than chocolate from beans grown at higher, cooler elevations.

Still, the temperature variances are relatively narrow, so the ranges used here generally work for dark chocolates. Milk chocolates require slightly cooler temperatures, because the additional ingredients affect the melting points of the different crystalline forms. When looking at chocolate for tempering, make sure it does not have other fats or lecithin added, because these ingredients affect the melting point.

Luckily for chocolate lovers worldwide, chocolate has two quirks that make it so enjoyable. For one, the undesirable forms of fat all melt below 90F / 32C, while the desirable forms noticeably melt around 94F / 34.4C. If you heat the chocolate to a temperature between these two points, the undesirable forms melt and then solidify into the desirable form.

The second happy quirk is a matter of simple biology: the temperature of the inside of your mouth is in the range of 9598.6F / 3537C, just above the melting point of tempered chocolate, while the surface temperature of your hand is below this point. Sure, a certain sugar-coated candy is known to be made to "melt in your mouth, not in your hands," but with properly tempered dark chocolate, the sugar coating isn't necessary (it is necessary for milk chocolate, though, which melts at a temperature lower than that of your hand).

NoteM&Ms were developed in 1940 by Frank C. Mars and his son, Forrest Mars, Sr. During the Spanish Civil War (19361939), Forrest saw Spanish soldiers eating chocolate that had been covered in sugar as a way of "packaging" the chocolate to prevent it from making a mess.

How does all of this relate to sous vide cooking? Traditional tempering works by melting all forms of fat in the chocolate, cooling it to a low enough temperature to trigger nucleation formation (i.e., causing some of the fat to crystallize into seed crystals, including some of the undesirable forms), and then raising it to a temperature around 90F / 32.2C, where the fats crystallize to make Form V crystals.

This three-temperature process requires a watchful eye and, during the second step, constant stirring to encourage the crystals to form while keeping them small. Water baths allow for a shortcut in working with chocolate: already tempered chocolate doesn't need to be tempered if if you don't get it any hotter than around 91F / 32.8C. The desirable forms of fat won't melt, so you're good to go. To melt already tempered chocolate, seal it in a vacuum bag and submerge it in a water bath set to 91F / 32.8C. (You can go a degree or so warmer; experiment!) Once it's melted-which might take an hour or so-remove the bag from the water, dry the outside, and snip off one corner: instant piping bag. you don't get it any hotter than around 91F / 32.8C. The desirable forms of fat won't melt, so you're good to go. To melt already tempered chocolate, seal it in a vacuum bag and submerge it in a water bath set to 91F / 32.8C. (You can go a degree or so warmer; experiment!) Once it's melted-which might take an hour or so-remove the bag from the water, dry the outside, and snip off one corner: instant piping bag.

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Temperature versus time chart for melting and tempering chocolate.

If you're going to be working with chocolate on a regular basis, the sous vide hack will probably get tiring. It works, but if you have the dough to spend, search online for chocolate tempering machines. One vendor, ChocoVision, sells units that combine a heat source, a motorized stirrer, and a simple logic circuit that tempers and holds melted chocolate suitable for everything from dipping fruit to coating pastries to filling chocolate molds. Of course, if you have a slow cooker, thermocouple, and temperature controller...

Chocolate Almond BarsMy local grocery store recently started carrying specialty bars of chocolate infused with unusual ingredients: curry powder and coconut; plums, walnuts, and cardamom; even bacon bits. These exotic chocolate bars also carried exotic price tags, so I thought: how hard can it be to make these? With sous vide, it turns out it's downright simple.

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Place tempered chocolate in a vacuum bag. Use chocolate in bar form; chocolate chips might not work if they aren't as well tempered.Add your flavorings. Try almonds or hazelnuts (at about a 1:2 ratio-one part nuts to two parts chocolate by weight). Your ingredients should be dry. Any water in them will cause the chocolate to seize up.Seal, drop in a water bath set to 92F / 33.5C, and wait for chocolate to melt, which may take an hour or two.

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After the chocolate is thoroughly melted, work the bag to distribute the chocolate and flavorings. You can use a rolling pin to work the fillings around if using something like nuts.Let bag rest on counter to cool.

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Once cooled, snip the bag open and peel it off the chocolate. You can break the bar up into pieces.Try using coffee beans (yum), candied grapefruit rind, dried fruits such as cranberries, or a mix of toasted nuts (almonds, pistachio, and pecans, and maybe a pinch of cayenne pepper).

Flash Pickling with a Vacuum Sealer...or How to Void Your Warranty in Three Easy StepsOnce you have a sous vide setup, you also have most of the tools needed to do flash pickling. In the culinary world, flash pickling flash pickling refers to submerging a food item in a liquid-filled container, evacuating the container, and then repressurizing the container. Unlike traditional pickling, which requires time (or heat) to coerce the pickling liquid into the food, flash pickling is instant, hence its name. refers to submerging a food item in a liquid-filled container, evacuating the container, and then repressurizing the container. Unlike traditional pickling, which requires time (or heat) to coerce the pickling liquid into the food, flash pickling is instant, hence its name.Under vacuum, microscopic air pockets in foods like sliced apples and cuc.u.mber wedges lose their air. Upon returning to atmospheric pressure, the food expands back out to its original shape, a bit like a sponge. But because the food is submerged, liquid is pulled back in, instead of air. Why bother? Because "Manhattan apples" (use whiskey) or "martini pickles" (use gin) are just plain awesome awesome. See http://video.nytimes.com/video/2007/12/04/magazine/1194817116911/the-edible-martini.html for a video of Dave Arnold talking about the process using a commercial vacuum sealer. for a video of Dave Arnold talking about the process using a commercial vacuum sealer.[image]Cuc.u.mbers being flash-pickled in gin using a consumer jar sealer attachment.The pros, who use commercial vacuum chambers, can just drop the food into the liquid bath and clamp down on the lid. For the rest of us, though, generating a sufficiently strong vacuum isn't so easy. But if you have a vacuum food sealer and don't mind voiding your warranty, there is a way.NoteI should have just written an entire chapter called "Voiding Your Warranty."Consumer vacuum sealers have a pressure switch that triggers them to stop pumping and start sealing, meaning that they stop short of creating a strong enough vacuum to create a good pickle. But if you disable the pressure switch, the unit should continue to pump indefinitely, or until the motor burns out.To make a DIY flash-pickling system, start with a consumer vacuum sealer. You'll need a toggle switch and an extra piece of wire, along with a screwdriver and wire cutters.[image]Start by popping open the vacuum sealer. It should look something like this.[image]Locate the pressure switch (highlighted on left). Cut one of the wires that runs back to the circuit board and interpose a toggle switch (highlighted on right). Cut a small hole in the plastic and mount the toggle switch so that you can flip it from the outside.PHOTOS USED BY PERMISSION OF CARL HILL-POPPER

Commercial Hardware and Techniques What goes on behind those two-way swinging doors leading to the commercial kitchen? More and more restaurants are sharing with the public what they're doing, even going so far as to blog their thoughts and recipes for all the world to see. Why? Well, for one, it serves as great publicity for the restaurants. And secondly, so much of what's done in the high-end modernist restaurants requires so much work that it's probably cheaper for a home chef to go and eat at the restaurant than it would be to try undertaking one of their recipes anytime soon.

Even if you're not going to attempt a full 26-course dinner, you can learn a lot by seeing how the pros approach food and the lengths to which they go to in their quest for a truly fantastic and delightful meal.

Since the techniques in this section are not, in and of themselves, going to put dinner on the table, you might wonder how to work them into your cooking. Think of this section like knife skills for modernist cuisine: a few pointers for what's happening behind those swinging doors. For inspiration and ideas of what to do with these skills, try turning to the Internet. Here are a few blogs worth checking out (most of these are a.s.sociated with interviewees in this book as well): - Cooking Issues ( (http://cookingissues.com) - Nils Noren, Dave Arnold, and other members of the French Culinary Inst.i.tute blog about their investigations into cooking phenomena, giving good explanations of how to use new technologies.

- eGullet.org ( (http://forums.egullet.org) - The mother of all forums related to food, eGullet is home to many threads covering almost any topic you can imagine related to the creation of food, including the infamous sous vide thread.

- Ideas in Food ( (http://blog.ideasinfood.com) - Alexander Talbot and Aki Kamozawa blog about their work with food, sometimes including insightful recipes and tips.

- Playing with Fire and Water ( (http://www.playingwithfireandwater.com) - Linda Anctil's blog posts give an evocative and creative approach to food.

In this section, we'll take a look at a few techniques that are common in commercial restaurants and examine ways that they can be useful to the home chef. This isn't by any means a complete list. Rather, this should be enough to get you started thinking outside the box (or, harking back to the functional fixedness concept discussed in the opening chapter, getting to see the box in a different way).

3D Printing and Mold MakingMany aspects of "playing with your food" are beyond the reach of most commercial restaurants, either because they're not worth the time or require a geek to do it.For a few high-end restaurants, spending the time involved in making custom molds allows them to create innovative and unusual experiences. Working with fabricators, they'll create custom silicone molds ranging in shapes of everything from vegetables to eggs, using them to mold asparagus puree set with gelling agents or for signature desserts.[image]Then there's the geek side of things. If you happen to have access to a CNC (computer numeric control) printer, such as MakerBot's Cupcake, try printing your own molds and cookie cutters. Here's an example, using none other than that famous penguin, Tux. (Tux is the Linux kernel's official mascot.) You'll need a cookie cutter, sugar cookie dough, and frosting.Create the cookie cutter. This is the hardest part (second hardest, if you're the type to eat all the cookie dough before getting to the end). a.s.semble a MakerBot CNC printer and print a Tux cookie cutter, following the STL and G code files at This is the hardest part (second hardest, if you're the type to eat all the cookie dough before getting to the end). a.s.semble a MakerBot CNC printer and print a Tux cookie cutter, following the STL and G code files at http://www.cookingforgeeks.com/book/cookie-cutter/.Bake the cookies. Using the cookie cutter (shown on the left in the photo below), create your Tux cookies and bake. Allow the cookies to cool before frosting. Using the cookie cutter (shown on the left in the photo below), create your Tux cookies and bake. Allow the cookies to cool before frosting.[image]Frost. Until MakerBot comes out with a Frostruder that supports multiple colors, you'll have to do this by hand. Prepare a batch of frosting (see Until MakerBot comes out with a Frostruder that supports multiple colors, you'll have to do this by hand. Prepare a batch of frosting (see Baking Soda Baking Soda in in Chapter5 Chapter5 for a simple frosting recipe) and divide it into three bowls, putting most of the frosting in the first bowl. Add yellow food coloring to the second bowl; you'll use this for Tux's yellow feet and beak. Add red and blue food coloring to the final bowl; when mixed together, this will make an almost-black frosting. for a simple frosting recipe) and divide it into three bowls, putting most of the frosting in the first bowl. Add yellow food coloring to the second bowl; you'll use this for Tux's yellow feet and beak. Add red and blue food coloring to the final bowl; when mixed together, this will make an almost-black frosting.To frost, take a first pa.s.s using the white frosting, covering the entire cookie in a single full layer of white frosting. Using a dinner knife, take a second pa.s.s, lightly smearing the yellow frosting for his beak and feet. For the third pa.s.s, transfer the black frosting to a plastic sandwich bag, snipping off the corner to make a piping bag, and carefully dot the two eyes and black edge.[image][image]

Filtration Filtering is a common technique for separating solids from liquids in a slurry. Filtering is usually done to remove the solids-for example, to create a clear broth free of particulate matter or a juice free of pulp. Other times, the solid matter, such as browned b.u.t.ter solids, is the desired item.

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Sizes of common items (top portion) and common filters (bottom portion).

Besides filtration, which we'll talk about here, additives can be used to separate out some types of solids. Some manufacturers use isingla.s.s, a collagen derived from fish bladders, in beer and wine making. The isingla.s.s binds with yeast and causes it to precipitate out. (Sorry, vegetarian beer lovers.) And consomme is traditionally clarified using egg whites, which, like isingla.s.s, bind to small particulates and then coagulate into a large ma.s.s that's easily removed. Mechanical filtration, in contrast, has the advantage of being fast and easy.

Reasons for filtering in the kitchen can range from aesthetic (including traditional broths like consomme) to practical (needing particulate-free liquid to work with in cream whippers, as described later in this chapter-the particulate would potentially clog the system).

Which type of filter to use depends on the size of the solids. A chinois chinois-a conical strainer-is fine for straining out spices and solids from a broth and is the standard go-to item for filtration. To mechanically mash foods and give them a finer texture, you can push them through a perforated sheet of steel. Traditional European soups, such as vichyssoise (potato and leek), pa.s.s through these to ensure a smoother mouth-feel.

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A standard modern technique for making clarified liquids such as consommes is to freeze the liquid and drip-thaw it through a filter, such as a Superbag.

High-end chefs use finer filtration to achieve other effects. Straining out the solids in tomato juice to get a clear, transparent tomato water requires a much finer filter. You can also use hydrocolloids: create a gel with gelatin (e.g., stocks) or agar (e.g., Dave Arnold's lime juice in The Easier, Cheaper Version of "The $10,000 Gin and Tonic" The Easier, Cheaper Version of "The $10,000 Gin and Tonic"), and pa.s.s the gel through a filter. The gel will hold on to most of the solids, while the filter will hold on to the gel.

International Cooking Concepts sells a filter bag called a "Superbag" that's dishwasher safe, reusable, and highly durable. For a tenth of the price, McMaster-Carr sells mesh filter bags that are FDA compliant and rated to 220F / 104.4C. Search for part 6805K31 on http://www.mcmaster.com.

NoteIf I were to write a "cooking geek purity quiz," one question would definitely be "How many things have you ordered from McMaster-Carr?"

The McMaster-Carr product uses a stiffer material and doesn't drain as quickly as the Superbag, however. With this size of filtration, you can quickly create flavored liquids such as nut milks (puree presoaked almonds, drop in filtration bag, squeeze liquid out) or fruit juices (puree cantaloupe, drop in filtration bag, squeeze liquid out). Try other things, such as asparagus and olives.

These finer filters can also be used for drip filtration, where the solids are rested in the filter bag and the liquids are given time to percolate out slowly. Puree tomatoes, drop them in a fine (~100 micron) filter sleeve, clamp in a storage container, and let drip overnight in the fridge to create semiclear tomato water.

Stock, broth, and consomme Stock, broth, consomme-what's the difference? Stock Stock and and broth broth are both liquids made by simmering vegetable and/or animal matter. Traditionally, stocks are made with bones, which have collagen. Most of this collagen breaks down and converts to gelatin, which gives the stock a lubricious mouth-feel and, at sufficient concentrations, causes the stock to turn into a gel when cooled. The cans of "stock" that you find in the grocery store are really broth-they don't have the same level of gelatin that a proper stock should have. are both liquids made by simmering vegetable and/or animal matter. Traditionally, stocks are made with bones, which have collagen. Most of this collagen breaks down and converts to gelatin, which gives the stock a lubricious mouth-feel and, at sufficient concentrations, causes the stock to turn into a gel when cooled. The cans of "stock" that you find in the grocery store are really broth-they don't have the same level of gelatin that a proper stock should have.

NoteIf the canned "stock" carried in grocery stores had gelatin, it would be gelled like Jell-O.

Stocks are generally more of an ingredient-not highly seasoned, usually added to a soup or dish. Broth is a finished product, and strictly speaking broths should be made without bones; they contain no gelatin and so are comparatively much thinner than stocks. From a practical perspective, in home cooking you can treat them as the same thing in most cases. Just don't try to make a dish such as aspic that relies on gelatin using broth.

Both stock and broth contain fats and solid particulate matter from the vegetable and animal products they're made with, giving them a cloudy appearance. A consomme consomme is a clarified version of either stock or broth, from which the particulates and some of the fats have been filtered out. The traditional method for clarification involves creating an egg-white "raft" that is gently stirred while the broth is simmered. It's time-consuming, and while you should try it sometime, it's not likely to be an everyday cooking technique. An easy modern method involves using the gelatin present in a true stock to trap the particulate matter. Freeze the stock, and as it thaws, the gelatin will hold on to the particulate matter; thaw it in a filter that's fine enough to hold onto the gelatin, and the resulting liquid that pa.s.ses through the filter will be consomme. is a clarified version of either stock or broth, from which the particulates and some of the fats have been filtered out. The traditional method for clarification involves creating an egg-white "raft" that is gently stirred while the broth is simmered. It's time-consuming, and while you should try it sometime, it's not likely to be an everyday cooking technique. An easy modern method involves using the gelatin present in a true stock to trap the particulate matter. Freeze the stock, and as it thaws, the gelatin will hold on to the particulate matter; thaw it in a filter that's fine enough to hold onto the gelatin, and the resulting liquid that pa.s.ses through the filter will be consomme.

"Filtering" by EvaporationOkay, this isn't really filtering in the true sense of the word, but you can can separate a liquid from any compounds dissolved in it by boiling off the liquid. Think sea salt: salt.w.a.ter is allowed to evaporate, leaving behind just the salt. separate a liquid from any compounds dissolved in it by boiling off the liquid. Think sea salt: salt.w.a.ter is allowed to evaporate, leaving behind just the salt.A rotary evaporator (rotovap) is nothing more than a fancy (and unfortunately very expensive) tool for replicating what happens in a salt flat, but it's designed to enable better control and to allow capturing of both parts (i.e., the salt and and the water after separating). It separates a solvent from a liquid or solid by gently boiling it away under a precise vacuum and temperature and then condensing the vapor in a flask, a process known as the water after separating). It separates a solvent from a liquid or solid by gently boiling it away under a precise vacuum and temperature and then condensing the vapor in a flask, a process known as distilling distilling. It's like boiling water on the stove and collecting the steam that condenses on the lid, but with far more precision.Distilling under a vacuum lowers the boiling point of the solvent (usually water or ethanol), meaning that any compounds that are heat-unstable remain undisturbed. With a rotovap, alcohol or water can be boiled off without the changes in flavor that normally come about from cooking. Chefs have made flavorings using everything from common vanilla to offbeat items such as "sea" (using sand) and "the woods" (damp dirt from the forest). Rotovaps can also be used to remove solvents from a food-removing alcohol to make whiskey essence, water to increase the concentration of fresh-squeezed juices, or both alcohol and water to make sauces such as port syrup.Unfortunately, commercial rotovaps are expensive, expensive, and the process of distilling foods is heavily regulated. For all the details, see the Cooking Issues blog writeup at and the process of distilling foods is heavily regulated. For all the details, see the Cooking Issues blog writeup at http://www.cookingissues.com/primers/rotovap/.Basic White StockIn a large stockpot (6 qt / 6 liter), add the following and sweat the vegetables until they begin to soften, about 5 to 10 minutes: - 2 tablespoons (25g) olive oil - 1 (100g) carrot, diced - 2 (100g) celery ribs, diced - 1 medium (100g) onion, diced Add: - 4 pounds (2kg) bones, such as chicken, veal, or beef For bones, look for "chicken backs" in your grocery store.Cover with water and bring to a slow boil. Add aromatic herbs and spices, such as a few bay leaves, a bunch of thyme, or whatever suits your taste. Try star anise, ginger root, and cinnamon sticks for something closer to the stock used in Vietnamese[image] . .Simmer for several hours (two to three for chicken bones; six to eight for thicker and heavier bones). Strain and cool; transfer to fridge.If you're worried about leaving the stove on, use a slow cooker.For a bit of overkill, here's what straining a batch of white stock in various ways yields, starting with the coa.r.s.est straining and going progressively finer. (I removed the bones and vegetable matter with a ~5,000-micron spider strainer before running the stock through the 500-micron filter.)[image]500 micron: stuff caught by a chinois or fine strainer[image]...then 300 micron: stuff caught by a cotton towel[image]...then 100 micron: stuff caught by a Superbag mesh filter.Drip-Filtered ConsommeConsomme made via drip-thawing stock (left), compared to the original stock (right) filtered at 100 microns. Note the transparency of the consomme-it looks like filtered apple juice.[image]To make a drip-filtered consomme, start with a proper stock. The gelatin is a necessary component, because it serves the same function as the egg-white raft in the traditional method.Once the stock has cooled and gelled (leave it overnight), transfer the gelatin to the freezer and let it freeze solid. As the water in the stock freezes, it will push the impurities into the gelatin. After it's frozen, put the stock into a filter bag or strainer lined with a cotton towel and let it drip-thaw on the counter for an hour, or in the fridge overnight. The filter or towel will hold on to the gelatin, and the gelatin will hold on to the smaller particles.Make sure the container you freeze the stock in is smaller than the filter bag you use; otherwise, you won't be able to fit the frozen block into the filter.[image]Place frozen stock in a strainer lined with a cotton towel. You can freeze the stock in ice cube trays, as shown here.[image]After an hour or two, the stock will have thawed, with the consomme in the pan and the cotton holding on to these weird blob shapes of gelatin.Dave Arnold on Industrial Hardware[image]PHOTO OF DAVE ARNOLD USED BY PERMISSION OF JEFF ELKINS, HTTP://JEFFELKINSPHOTO.COM HTTP://JEFFELKINSPHOTO.COMDave Arnold teaches at the French Culinary Inst.i.tute in New York City, where he instructs students about modern techniques and equipment. He also contributes to the excellent Cooking Issues blog at http://www.cookingissues.com.How do you get someone to make the mental leap, to think a.n.a.lytically, and to think outside the box, while in the kitchen?For people who don't naturally think this way, you can't expect them to start organically. You just want to give them another set of tools to work with in the kitchen. So we take something that they take for granted, like cooking eggs, and then break it into a zillion little components. We set up grids where we manipulate single variables. This means that we look at two variables at once in a grid format-for example, time against temperature-and manipulate one variable to see how it affects the other.One of the cla.s.sic examples is coffee. The variables are knowable, but why is so much coffee, specifically espresso, terrible? There are plenty of people that have machines that are good enough. It's good to think a.n.a.lytically. If you're messing around with coffee and you're changing x, y, and z, it's the equivalent of standing in front of a big control board with a bunch of dials and then just spinning the dials. To teach someone to make good coffee, you have to teach them how to lock down all their variables and then alter them one at a time. When you're making espresso, most people choose to alter their grinds as their variable. They find that it's easier to lock in the temperature, the dosing, the pressure, and then manipulate grinds. It teaches them how to manipulate variables and think a.n.a.lytically about something.If we're trying to figure out the variable of temperature with eggs, we'll just do it. I'll use a circulator to cook 10 eggs at very precise temperatures. We'll do it multiple times and we'll crack them and see what the behavior is. Or we'll teach people how to make grids to test two different variables in order to figure out something like the effect of heat on searing meat. We'll set up a tasting grid and they can taste it. I think this helps people to pick up that skill. It's all about control and the ability to observe.What sort of hardware have you repurposed for the kitchen?Basically, a chef is going to want to steal anything that can help them heat differently or h.o.m.ogenize or blend differently. Most of what we use that has been repurposed aren't necessarily our own ideas. You can crib things off of other people. Everyone is using liquid nitrogen now, which is fantastic stuff.Even stuff normally found in the kitchen we just use in a different way. A lot of people are doing interesting work with pressure cooking nowadays. We use ultrasonic cleaners and rotovaps a lot. We've been running some experiments on torches recently. Why do things that are hit with torches taste like torch? I'm beginning to think that it's the component added to gases to make them smell so that you can tell when you have a leak. I think the torch flavor is due to not fully combusting all of the stinky stuff. I wanted to crisp something big, and so I fired up the roofing torch with propane, and it didn't taste bad. I tried to shoot a regular torch through a screen to see whether we could combust any of the torch smell by capturing it on the screen and blowing it through. That also works.How do you balance experimenting with safety?Teach yourself as much as you can about the risks involved with any potential new endeavor. The Internet is also good for that, because there are plenty of people who've already hurt themselves. Do a lot of research; read a lot of things. There're a lot of opinions out there, and what one person says may not necessarily be true. It doesn't take too much Googling around to find out that someone has already tried to carbonate something by sticking dry ice in a soda bottle and gotten a bunch of shattered plastic in his face as a result.You don't want to stifle anyone's creativity or their desire to hack around and do things, because that's the fun of it. But it has to be tempered with a certain amount of base knowledge. Things are dangerous under three circ.u.mstances: one, if you don't know the procedure at all. That's what happened to the soda bottle guy. He didn't know the procedures. Two, you're completely frightened of something, a piece of equipment or a knife. If you decide to use it anyway, you're more likely to get hurt. Three, when you become complacent. If you're an inherently cautious person and you don't become complacent, that's the safest way to do these kinds of experiments.What about the safety of used equipment, such as lab gear?When I got my centrifuge, we bleached and pressure-cooked any parts that would touch any food. When I got my rotovap, I soaked that sucker in a bleach solution and then in boiling water, and then boiling water and bleach. You have biological contaminants and you have poisonous contaminants-all sorts of contaminants. I feel pretty okay that with stainless and gla.s.s I can get rid of most bad inorganic stuff, but you just have to pray that you wash enough to get rid of all the organic stuff. From a biological hazards standpoint, you're worried about prions, you're worried that someone has been blending up cow brains doing CreutzfeldtJakob research or something like that. You can't cook it away, they're heat-stable. Then you're counting on mechanical washing.I'm curious, what do you do with a centrifuge?A lot of people buy centrifuges because they think they're going to get awesome results with a centrifuge. What you really need to do is borrow someone else's first. All a centrifuge does is separate things based on density.If you're cooking, you want a lot of product, because you want to serve a lot of people. It's not often feasible. Unilever donated a centrifuge to us, and I had more time just to play around. Now we're doing a lot of things like making our own nut oils, or clarifying things like apple juice, where we're spinning it down to increase our yield. Also, you can blend olives, cured ones like kalamata, and then you spin them. It breaks into three layers. You have the best olive brine ever for a dirty martini, hands down. You have a completely flavorless middle layer you throw away. Then you have a really interesting layer of olive oil from cured olives. That's kind of fun. Expensive, though.We're taking things into the kitchen that aren't from the kitchen, not just laboratory equipment. There's a whole group of people that make their own chocolates. They use a stone grinder from India that's used to grind dahl. We've taken that, and we're making things that have the textural properties of chocolate, which aren't related to chocolate at all, like ketchup and mustard. Most stuff in the kitchen is going to be equipment-based, but it's not necessarily new technology or lab technology. Sometimes it's just learning new techniques. It's more of an att.i.tude.I'll give you another example: how are you supposed to cook mushrooms? You're not supposed to soak mushrooms. They always tell you to wipe off your mushrooms.I usually just do a quick wash. My take has always been that it doesn't actually absorb that much water.It actually does. Mushrooms are little sponges, but here is