Douglas Baldwin

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A Practical Guide to Sous Vide Cooking

Preface

Sous vide is French for "under vacuum" and describes a method of cooking in vacuum sealed plastic pouches at low temperatures for long times. With the proper equipment and some basic knowledge, anyone can prepare consistently delicious and safe food. With more advanced knowledge, a chef can safely create (or modify) recipes to realize their unique vision.

This guide attempts to distill the science of sous vide to provide anyone with the tools needed to safely realize their creative visions. Part I discusses the techniques and safety concerns of sous vide. Some prototypical recipes are explored in Part II. The mathematics of sous vide are detailed in Appendix A. Finally, Appendix B discusses the specialized equipment necessary for sous vide.

More information will be added over the coming weeks and months, so be sure to check back frequently.

Introduction

Sous vide is a method of cooking in vacuum sealed plastic pouches at low temperatures for long times. Sous vide differs from conventional cooking methods in two fundamental ways: (i) the raw food is vacuum sealed in a plastic pouch and (ii) the food is cooked using precisely controlled heating.

Vacuum sealing the food keeps the juices and vapors from escaping and results in especially flavorful and nutritious food [Sch96]. Vacuum sealing also reduces aerobic bacterial growth and oxidation, improves marination and seasoning, and allows for the efficient transfer of thermal energy from the water (or steam) to the food.

Consider the problem of cooking a thick-cut steak medium-rare. Cooking the steak on a grill at over 1,000°F (500°C) until the center comes up to 120°F (50°C) will result in everything but the very center being overcooked. A common solution is to sear one side of the steak in a pan, flip the steak over, and place the pan in a 275°F (135°C) oven until the center comes up to 131°F (55°C). For sous vide, the steak is vacuum sealed in a plastic pouch, cooked in a 131°F (55°C) water bath for a couple hours, and then seared in a smoking hot pan or with a blowtorch; the result is a medium-rare steak with a great crust that is the same doneness at the edge as it is at the center. Moreover, the flavorful flat iron steak can be cooked (very safely) in a 131°F (50°C) water bath for 24 hours and will be both medium-rare and as tender as filet mignon.

Figure 1: Pictures of intact eggs cooked in a water bath for 75 minutes at temperatures ranging from 136°F (57.8°C) to 152°F (66.7°C). From left-to-right and top-to-bottom, the water bath temperature was 136.0°F (57.8°C), 138.0°F (58.9°C), 140.0°F (60.0°C), ..., 152°F (66.7°C).

Precise and accurate temperature control is important. Consider the so called "perfect egg" which is cooked intact in a water bath at 148°F (64.5°C) for one hour. Figure 1 shows that a difference of only 2°F (1°C) results in dramatically different eggs. Thus, in order to consistently achieve a desired result, the cooking medium must be both accurate and stable.

In almost all cases, the cooking medium is either a water bath or a convection steam oven. Convection steam ovens allow large quantities of food to be prepared, but gas (electric) models often have temperature swings of up to 10°F/5°C (5°F/2.5°C). In comparison, circulating water baths often have temperature swings of less than 0.1°F (0.05°C). It is not surprising then that water baths are the preferred choice of most chefs. Since cooking times and temperatures are the same for both convection steam ovens and water baths, I will assume throughout that a water bath is being used.

Part I: Technique

1. Basic Technique

Sous vide typically consists of three stages: preparing for packaging, cooking and finishing.

Preparing for Packaging

Seasoning

Seasoning can be a little tricky when cooking sous vide: while many herbs and spices act as expected, others are amplified and can easily overpower a dish. Additionally, aromatics (such as carrots, onions, celery, bell peppers, etc.) will not soften or flavor the dish as they do in conventional cooking methods because the temperature is too low to soften the starches and cell walls. Indeed, most vegetables require much higher temperatures than meats and so must be cooked separately. Finally, raw garlic produces very pronounced and unpleasant results and powdered garlic (in very small quantities) should be substituted.

For long cooking times (of more than a couple hours), some people find that using extra virgin olive oil results in an off, metallic, blood taste. (Since the extra virgin oil is unheated and unrefined during production, it is reasonable that some of the oil will breakdown even at a low temperature if give enough time.) A simple solution is to use grape seed or any other processed oil for longer cooking times; extra virgin olive oil can then be used for seasoning after cooking.

Marinating, Tenderizing and Brining

Since todays meat is younger and leaner than the meat of the past, many cooks marinate, tenderize or brine the meat before vacuum packaging.

Most marinades are acidic and contain either vinegar, wine, fruit juice, buttermilk or yogurt. Of these ingredients, only wine presents any significant problems when cooking sous vide. If the alcohol is not cooked off before marinating, some of it will change phase from liquid to vapor while in the bag and cause the meat to cook unevenly. Simply cooking off the alcohol before marinating easily solves this problem.

Mechanical tenderizing with a Jaccard has become quite common. A Jaccard is a set of thin blades that poke through the meat and cut some of the internal fibers. The Jaccard does not typically leave any obvious marks on the meat and is often used in steak houses. By cutting many of the internal fibers that would typically contract with heat and squeeze out the juices, it can slightly reduce the amount of moisture lost during cooking. For instance, when cooking a chuck steak for 24 hours at 131°F (55°C) the Jaccarded steak lost 18.8% of its weight compared to 19.9% for the non-Jaccarded steak. In general, more liquid weight is lost the longer a piece of meat is cooked at a given temperature---however, this additional weight loss is balanced by the increased tenderness from collagen dissolving into gelatin.

Brining has become increasingly popular in modern cooking, especially when cooking pork and poultry. Typically the meat is placed in a 3 to 6% (30 to 60 grams per liter) salt solution for a couple of hours, then rinsed and cooked as usual. Brining has two effects: it dissolves some of the support structure of the muscle fibers so they cannot coagulate into dense aggregates and it allows the meat to absorb up to 10% of its weight in water [McG04]. While the meat will still lose around 20% of its weight when cooked, the net effect will only be a loss of about 12% of its original weight.

Cooking

There are two schools of thought when cooking sous vide: either the temperature of the water bath is (i) just above or (ii) significantly higher than the desired final core temperature of the food. While (ii) is closer to traditional cooking methods and is used extensively in [RB05], (i) has several significant advantages over (ii). Through out this guide, I define just above as 1°F (0.5°C) higher than the desired final core temperature of the food.

When cooking in a water bath with a temperature significantly higher than the desired final core temperature of the food, the food must be removed from the bath once it has come up to temperature to keep it from overcooking. This precludes pasteurizing in the same water bath that the food is cooked in. Since there is significant variation in the rate at which foods heat (see Appendix A), a needle temperature probe must be used to determine when the food has come up to temperature. To prevent air or water from entering the punctured bag, the temperature probe must be inserted through closed cell foam tape. Even when using closed cell foam tape (which is similar to high density foam weather stripping), air will be able to enter the plastic pouch once the temperature probe is removed.

In contrast, cooking in a water bath with a temperature just above the desired final core temperature of the food means the food can remain in the water bath (almost) indefinitely without being overcooked. Thus, food can be pasteurized in the same water bath it is cooked in. While cooking times are longer than traditional cooking methods, the meat comes up to temperature surprisingly quickly because the thermal conductivity of water is 23 times greater than that of air. Moreover, temperature probes are not necessary because maximum cooking times can be tabulated (see Tables 1.2 and 1.3).

Tender Meat

When cooking tender meats, we just need to get the center up to temperature and, if pasteurizing, hold it there from some length of time. (For more information on pasteurization, see Chapter 2.) Cooking times depend critically on the thickness of the meat: doubling the thickness of the meat increases the cooking time four  fold!

While there is no consensus as to what temperatures rare, medium-rare and medium correspond to, I use the temperatures in Table 1.1. The approximate cooking times for thawed and frozen meats are given in Tables 1.2 and 1.3. For a complete discussion on how these times were computed, please see Appendix A.

If the food is not being pasteurized (as is the case with fish and rare meat), it is important that the food come up to temperature and be served within four hours. (See Chapter 2 for more information on food safety.) Unlike conventional cooking methods, this is easily accomplished by cutting the food into individual portion sizes before cooking---which is why cooking times over four hours are not shown for temperatures below 131°F (55°C).

Tough Meat

When cooking tough meats, two processes are of particular importance: the dissolving of collagen into gelatin and the melting of solid (saturated) fats.

Before sous vide cooking, the dissolving of collagen into gelatin required cooking meat well done (between 160°F/70°C and 180°F/80°C) and holding it at that temperature for a couple of hours. The reason being that while collagen begins to dissolve at 131°F (55°C) [Thi06], it must be held at that temperature for 12--72 hours to have a significant effect---something impossible to achieve with conventional cooking methods. However, thanks to sous vide's precise temperature control, it is both possible and quite common to cook tough cuts of meat for 24--48 hours at 131°F (55°C).

While collagen will begin to dissolve at 131°F (55°C), only 5--10% of the saturated fat in pork and beef will melt at that temperature. Nearly 60% of the saturated fat in pork and beef, the saturated fatty acid palmitic, melts at 145°F (62.8°C). The remaining 30--35%, the saturated fatty acid stearic, melts at 157°F (69.6°C).

Chilling for Later Use

In the food industry, sous vide is used to extend the shelf life of cooked foods. After pasteurizing, the food is rapidly chilled in its vacuum sealed pouch and refrigerated (or frozen) until needed. Before finishing for service, the food is then reheated in a water bath at or below the temperture it was cooked in. Typically, meat is reheated in a 131°F (55°C) water bath for the times listed in Tables 1.2 or 1.3 since the optimal serving temperature for meat is between 120--130°F (50--55°C).

The danger with cook-chill is that pasteurizing does not reduce pathogenic spores to a safe level. If the food is not chilled rapidly enough or is refrigerated for too long, then pathogenic spores can outgrow and multiply to dangerous levels. For cooling and refrigeration guidelines, see Chapter 2.

Finishing for Service

Since sous vide is essentially a very controlled and precise poach, most food cooked sous vide has the appearance of being poached. So foods like fish, shellfish, eggs, and skinless poultry can be served as is. However, steaks and pork chops are not traditionally poached and usually require searing or saucing. Searing the meat is particularly popular because the Maillard reaction (the browning) adds considerable flavor. It is important to sear the meat at a very high heat, so that the surface is browned but the meat does not become overcooked. The most popular method of searing is to use a blowtorch. While many use a hardware propane blowtorch, I highly recommend using an Iwatani butane blowtorch. Both propane and butane can burn at over 3,500°F (1,900°C) in air, but propane blowtorches often leave an off flavor. Other chefs prefer to pan sear using a heavy cast iron pan with just smoking pure vegetable or nut oil---which smoke at 400°F to 500°F (205°C to 260°C).

2. Safety

Our goal is to maximizing taste while minimizing the risk of food pathogens. Although pathogenic microorganisms can be controlled with the addition of acids, salts and spices, sous vide foods rely heavily on temperature control [RR01].

The myth of the "danger zone" of 40°F to 140°F (4°C to 60°C) is absurd. It is well known that food pathogens can multiply between 29.3°F and 127.5°F (-1.6°C and 53°C), while spoilage bacteria begin to multiply at 23°F (-5°C) [Sny06]. Moreover, contrary to popular belief, most food pathogens and toxins cannot be seen, smelt or tasted.

All sous vide prepared foods can be divided into three categories: (i) raw or unpasteurized, (ii) pasteurized, and (iii) sterilized. Pasteurization means heat treating the food to reduce the number of vegetative pathogens to a safe level. Vegetative pathogens are simply active bacteria that are growing and multiplying. Some bacteria are also able to form spores which are very resistant to heat and chemicals. Heat treating food to reduce both the vegetative microorganisms and the spores to a safe level is called sterilization¹.

Pasteurized foods must either be eaten immediately or rapidly chilled and refrigerated to prevent the outgrowth and multiplication of spores. Moreover, the center of food should reach 130°F (54.4°C) within 6 hours to prevent the toxin producing pathogen Clostridium perfringens from multiplying to dangerous levels [Sny06].

Raw or unpasteurized food must not be served to highly susceptible or immune compromised populations. Even raw fruits and vegetables should be twice washed² before serving. For raw and unpasteurized foods, it is important that they be consumed before food pathogens have had time to multiply to harmful levels. With this in mind, the US Food Code requires that food must not be above 41°F (5°C) for more than 4 hours [Foo05,3-501.19.B]. The reason being that Vibrio parahaemolyticus---which is commonly present in raw fish and seafood---can double every 7 to 8 minutes at 95°F (35°C) and can multiply to hazardous levels in only 2 to 3 hours [Sny99].

Pasteurization is a combination of both temperature and time. Consider the very common food pathogen Salmonella spp. At 140°F (60°C), all the Salmonella doesn't instantly die but is reduced by a factor ten (10) every 1.73 minutes [Sny99]. This is often referred as a one decimal reduction and is written D[140°F (60°C)] = 1.73 minutes. Meat is considered safe after 6.5 to 7 decimal reductions of Salmonella [FIS05] or after 7D[140°F (60°C)] = 12.1 minutes.

The rate at which the bacteria die depends on many factors, including temperature, acidity, salt content, certain spices, and water content. For instance, at 130°F (54.4°C) a 7D reduction in Salmonella takes 121 minutes, while at 150°F (65.6°C) it takes only 73 seconds. The pasteurization times for beef, lamb and pork are listed in Table 2.1. Table 2.2 lists the pasteurization times for chicken and turkey. The addition of acids, salts or spices can all decrease the number of vegetative pathogens---this is why mayonnaise (with a pH less than 4.1) does not need to be heat treated.

There are many food pathogens other than Salmonella, but Salmonella is often used as the time-temperature standard for pasteurization [Sny99]. While Listeria monocytogenes is the most heat resistant (nonspore forming) pathogen, [Nat91] only requires a 4D reduction in beef and poultry---a level that is achieved by the time a 7D reduction in Salmonella is achieved³. Although Salmonella stops growing at 114°F (45.6°C), the lowest temperature for pasteurization is 130°F (54.4°C) because the common food pathogen C. perfringens can grow at temperatures up to 127.5°F (52.3°C).

While keeping the food sealed in plastic pouch prevents recontamination after cooking, spores of Clostridium botulinum, C. perfringens and Bacillus cereus can all survive the mild heat treatment of pasteurization. Therefore, the food must either be served immediately or rapidly cooled and refrigerated at

1. below 36.5°F (2.5°C) for up to 90 days,
2. below 38°F (3.3°C) for less than 31 days,
3. below 41°F (5°C) for less than 10 days, or
4. below 50°F (10°C) for less than 5 days

A few sous vide recipes, such as duck, pork and turkey confit, use temperature-time combinations which can reduce non-proteolytic C. botulinum to a safe level; specifically, a 6D reduction in non-proteolytic C. botulinum requires 363 minutes (6 hours and 3 minutes) at 176°F (80°C) or 36 minutes at 185°F (85°C) [Pec97]. The food may then be stored at below 50°F (10°C) indefinitely (the minimum temperature at which proteolytic C. botulinum and C. perfringens can grow). If the food was vacuum sealed using a clamp style vacuum sealer, then there is sufficient air left in the package for B. cereus to grow and the food should be stored at below 39°F (4°C) [RR01].

Part II: Recipes

3. Fish and Shellfish

Fish lends itself particularly well to being cooked sous vide. Since sous vide brings out the natural flavors of the fish, it is important that only very fresh fish which still smells of the sea be used. When purchasing fish, the flesh should be shiny, moist and firm to the touch; have your fishmonger package the fish with ice and store the fish on ice in your refrigerator. Just before cooking, always check for and remove any scales or pin bones (with needle-nose pliers or tweezers).

Most fin and shellfish are best cooked medium (130°F/54.5°C) to medium-rare (120°F/49°C). The exceptions being arctic char and salmon which are best cooked medium-rare (120°F/49°C) to rare (110°F/43°C) and tuna which is best cooked rare (110°F/43.5°C) to very rare (100°F/38°C). Fish cooked to a medium doneness (130°F/54.5°C) can be pasteurized in a 131°F (55°C) water bath if cooked for the times in Table 3.1.

When cooking fish rarer than medium (130°F/54.5°C), it is important to limit the time from refrigerator to table to be less than 4 hours. The reason being that the pathogen C. perfringens is able to grow at temperatures up to 127.5°F (53°C) and can multiply to dangerous levels in only 4--6 hours. (Although C. perfringens is not typically associated with fin and shellfish, the release of untreated wastewater into the ocean has resulted in high levels of C. perfringens in some fish populations [EMV98].) Moreover, fish which is not pasteurized should never be served to immune compromised populations.

Salmon

The texture of sous vide prepared salmon is very moist and tender. To contrast this texture, the skin should be removed before vacuum packaging, crisped and served as garnish.

A common problem when cooking salmon, is that the protein albumin leaches out of the fish and coagulates unattractively on the surface. This can be easily prevented by brining the fish in a 10% salt water solution for 10 minutes.

4. Poultry and Eggs

Perfect Egg

The custardy texture of the white and yolk of the so called "perfect egg" is caused by the denaturing of the egg protein conalbumin at 148°F (64.5°C). In Figure 1, we observe that the denaturing of the protein ovotransferrin at 144°F (62°C) causes the egg white to coagulate [Thi06].

Place egg in a 148°F (64.5°C) water bath for 45 minutes to 1 hour. Crack egg and serve immediately.

Pasteurized in Shell Egg

While only 1 in 10 000--20 000 intact shell eggs contain hazardous levels of Salmonella enteritidis [McG04,Sny06], Grade A eggs were implicated in 82% of outbreaks between 1985 and 1991 [MKL⁺94]. Therefore, when working with highly susceptible or immune compromised populations, pasteurized eggs should always be used in dishes which call for raw eggs (e.g., chocolate mousses).

Place egg in a 135°F (57°C) water bath for at least 1 hour and 15 minutes [SSVB97].

Pasteurized intact eggs can be stored and used whenever raw eggs are called for. While the properties of the egg yolk are unaffected, the egg white is milky compared to a raw egg. Whipping time is significantly longer for pasteurized eggs, but the final whip volume is nearly the same [SSVB97].

Chicken or Turkey Breast

Traditionally, light poultry meat is cooked well-done (160--175°F/71--79.5°C) for "food safety" reasons. When cooking chicken and turkey breasts sous vide, they can be cooked to a medium doneness (140°F/60°C) while still being pasteurized for safety.

Turkey, Duck or Goose Leg Confit

5. Beef

For tender cuts of beef---such as tenderloin, sirloin and rib-eye---season the meat, vacuum seal and cook very-rare (120°F/49°C), rare (125°F/51.5°C) or medium-rare (130°F/54.5°C) for the time listed in Table 1.2. [If serving immune compromised individuals, meats cooked medium-rare can be pasteurized for the times listed in Tables 5.1 or 5.2.] Then sear using either a blowtorch, a very hot grill, or a pan with just smoking oil.

For tough but flavorful cuts of beef---such as top blade, chuck, and top round---season the meat and cook in a 131°F (55°C) water bath for 24--48 hours. This is the lowest temperature that beef can safely be cooked at for extended periods of time. It is also the temperature at which collagen begins to dissolve into gelatin [Thi06].

Flat Iron Steak

Beef cooked in a vacuum will look paler than medium-rare when first cut, but will get redder once exposed to oxygen.

Roast Beef

Brisket

6. Pork

Traditional Style Pork Chops

Slow Cooked Pork Chops

Pulled Pork or Pork Confit

Rendering Lard (or Tallow)

Part III: Appendix

A. The Mathematics of Sous vide

The transfer of heat is well approximated by the 1D linear heat equation,

Figure 2: Plot of temperature (°C) verse time (minutes) of a 27 mm thick piece of Mahi-Mahi cooked in a 131°F (55°C) water bath. The blue dots are the core temperature measured using a ThermoWorks MicroTherma2T with a needle proble. The red line is the calculated core temperature and the blue line is the calculated surface temperature of the Mahi-Mahi (where I used a thermal diffusivity of 1.24 mm2/sec and a heat transfer coefficient of 1000 W/m2-K).

The surface temperature is determined using [SMOEVR06]

For white chicken meat, on average α = 1.389 mm²/sec since k = 0.506±0.0321 W/m-K, ρ = 1.038±0.0374 g/cm³, and C_p = 3.530±0.325 J/g-K [STM07]. Going out two standard deviations (so as to be in a 97.7% confidence interval⁴), I take α = 0.956 mm²/sec in all calculations. Moreover, the lowest values for pork and beef I found in the literature are α_pork = 1.12 mm²/sec [SMOEVR06] and α_beef = 1.03 mm²/sec [GSAdV06].

Using the above model for the temperature at the center of the meat, the classical model for the log reduction in pathogens is

B. Equipment

Digital Thermometers

Accurate temperature control is important for safe sous vide cooking. Pasteurization times depend critically on temperature. Many PID controlled water baths are off by 2°F (1°C) or more; so if a water bath is set at 141°F (60.5°C) it might only really be 139°F (59.5°C), and would mean a chicken breast needs 15 minutes more than expect to be considered safe. It is highly recommended that any chef interested in sous vide invest in a high quality digital thermometer.

On the low end, I would highly recommend ThermoWorks' Super-Fast Thermapen (or ETI Ltd's Thermapen FR1 or FR5). Interchangeable probes are very useful in sous vide, so you may want to invest in either a ThermoWorks MicroTherma 2T or an Extech EA15.

Vacuum Sealers

For short cooking times, it is often possible to wrap the food in a high quality plastic wrap; however, it is difficult to keep the liquid released by the food in and the liquid from the water bath out. Moreover, if there is any air in the vacuum pouch, it will balloon during heating and insulate the food (since air is a very poor conductor of heat). Moreover, ballooning of the bag may cause it to float to the surface of the water bath and result in unevenly cooked food.

If you do not have (and do not want to buy) a vacuum packaging system, the best solution is to use the inexpensive Reynolds Handi-Vac; the vacuum is not as strong as clamp or chamber style vacuum sealers, but it is inexpensive and the bags have been tested and work well for everything from salmon to pork shoulder.

Most home cooks use clamp style vacuum sealers, such as FoodSaver and Seal-A-Meal. The problem with clamp or edge style vacuum sealers is that it is difficult to get a strong vacuum, the bags are expensive (compared to those used in chamber machines), and liquids tend to get sucked into the machine. The easiest solution for vacuum sealing liquids is to freeze them before sealing; for instance, freezing a small ice cube tray filled with extra virgin olive oil is especially convenient.

Some advanced home and many professional cooks use chamber style vacuum sealers (such as the Minipack MVS31). These machines are able to pull a much stronger vacuum than clamp style vacuum sealers, use less expensive bags ($0.12 per square foot verse $0.42 per square foot), and are able to package liquids without freezing. However, chamber vacuum sealers are much larger and heavier than clamp style vacuum sealers and cost more than ten times as much.

Water Baths and Steam Ovens

Temperature Controlled Rice Cookers, Steam Tables, Slow Cookers and Electric Burners

For short cooking times (such as when cooking fish), a pan of water on the stove can be used if the cook is willing to watch it closely and adjust the temperature by hand. However, this becomes increasingly tedious for longer cooking times and most cooks use a digital controller to regulate the temperature.

The simplest (and least expensive) digital controllers used for sous vide are on-off (or bang-bang) controllers, such as the Ranco ETC. When tested with a steam table, I found that the Ranco ETC kept the water bath within ±2.1°F (±1.2°C). This level of temperature control is sufficient for nearly all sous vide applications.

A particularly popular digital control for sous vide cooking is the PID controller by Auber Instruments or Fresh Meals Solutions. Unlike an on-off controller, it must be tuned to the cooking device being used; I found that after tuning that an Auber PID controller kept my steam table water bath to within ±0.7°F (±0.4°C).

With all these digital controllers, I highly recommend setting the temperature offset (measured near the temperature at which you wish to cook) using a high quality digital thermometer. Indeed, at the default settings the thermistors used in the above controllers can easily be off 2--4°F (1--2°C).

These temperature controllers are often used with either a a counter top food warmer (or steam table), commercial rice cooker, a electric (induction) burner, a slow cooker (or crock pot), or a roaster. The most important consideration when purchasing such a device is that it must use a manual switch (which will not be reset when the power is turned on and off by the temperature controller). Many people use a rice cooker, steam table or electric burner because they react faster than slow cookers and roasters (and so have less temperature over shoot). Moreover, because they are heated from below, rice cookers, steam tables and electric burners often have sufficient convection currents to keep the water temperature spatially uniform; uncirculated slow cookers and roasters can have cold spots of as much as 10--20°F (5--10°C). Regardless of the heating device, it is highly recommended that a circulator be used in conjunction with the temperature controller. The most popular options for circulating the water is an aquarium air bubbler---aquarium pumps which must be submerged in the water are not designed to operate at sous vide temperatures and quickly fail. Another popular options for circulating the water is a swamp cooler pump because it is not submerged in the water and is designed for continuous operation.

Laboratory Circulating Immersion Water Baths

Circulating laboratory water baths are extremely popular because they are able to keep a large volume of water (often up to 50 liters) to ±0.1°F (±0.05°C). Many were purchased used on eBay for $100--$200, but because of the increased demand from sous vide are now selling for $350--$500. A significant problem with buying used laboratory water baths is that they may have been used in conjunction with carcinogens and pathogens; it is recommend that they first be cleaned with bleach, then cleaned with vinegar, and finally rinsed with a 70% (140 proof) alcohol. With the rising price of used circulating water baths, many are buying new immersion circulators from PolyScience and Techne.

While some cooks purchase specially designed stainless steel or acrylic tanks for their immersion circulators, most use either a large stock pot or a steam table pan. I find that a countertop food warmer (designed to hold a full size steam table pan) to be especially convenient; these food warmers are insulated, hold about 20 liters of water, and if set at a temperature just below the cooking temperature will insure that if the circulator fails the food will not be ruined.

Computer Controlled Convection Steam Ovens

Convection steam ovens are able to cook large quantities of food, but gas models can have temperature swings of up to 10°F (5°C) and electrical models of around 5°F (2.5°C). While this will work for many recipes, it many not be sufficient for things like salmon mi-cuit and the perfect egg.

Basic Equipment Suggestions

The table below is meant to give an idea of the approximate cost of various sous vide setups.

Bibliography

[EMV98] Diane D. Edwards, Gordon A. McFeters, and M. Indira Venkatesan, Distribution of Clostridium perfringens and fecal sterols in a benthic coastal marine environment influenced by the sewage outfall from McMurdo station, Antarctica, Applied and Environmental Microbiology 64 (1998), 2596--2600.

[FIS05] Time-temperature tables for cooking ready-to-eat poultry products, Notice 16-05, Food Safety and Inspection Service, 2005.

[Foo05] Food code, Tech. report, U.S. Department of Health and Human Services, 2005.

[GBGB89] J. E. Gaze, G. D. Brown, D. E. Gaskell, and J. G. Banks, Heat resistance of Listeria monocytogenes in homogenates of chicken, beef steak and carrot, Food Microbiology 6 (1989), 251--259.

[GHI00] A. H. Geeraerd, C. H. Herremans, and J. F. Van Impe, Structural model requirements to describe microbial inactivation during a mild heat treatment, International Journal of Food Microbiology 59 (2000), 185--209.

[GSAdV06] Mariela Y. Glavina, Karina C. Di Scala, Roberta Ansorena, and Carlos E. del Valle, Estimation of thermal diffusivity of foods using transfer functions, LWT 39 (2006), 455--459.

[McG04] Harold McGee, On food and cooking: The science and lore of the kitchen, Scribner, New York, 2004.

[MKL⁺94] Ban Mishu, J. Koehler, L.A. Lee, D. Rodrigue, F.H. Brenner, P. Blake, and R.V. Tauxe, Outbreaks of Salmonella enteritidis infections in the United States, 1985--1991, Journal of Infectious Diseases 169 (1994), 547--552.

[Nat91] National Advisory Committee on Microbiological Criteria for Food, Listeria monocytogenes recommendations, International Journal of Food Microbiology 14 (1991), 185--246.

[Pec97] Michael W. Peck, Clostridium botulinum and the safety of refrigerated processed foods of extended durability, Trends in Food Science & Technology 8 (1997), 186--192.

[RB05] Joan Roca and Salvador Brugués, Sous vide cuisine, Montagud Editores, S.A., 2005.

[RR01] S. Rybka-Rodgers, Improvement of food safety design of cook-chill foods, Food Research International 34 (2001), 449--455.

[Sch96] Mia Schellekens, New research issues in sous vide cooking, Trends in Food Science and Technology 7 (1996), 256--262.

[SMOEVR06] María Elena Sosa-Morales, Ronald Orzuna-Espíritu, and Jorge F. Vélez-Ruiz, Mass, thermal and quality aspects of deep-fat frying of pork meat, Journal of Food Engineering 77 (2006), 731--738.

[Sny99] O. Peter Snyder, Jr., Food pathogen control data summary, Tech. report, Hospitality Institute of Technology and Management, 1999.

[Sny06] O. Peter Snyder, Jr., Food safety hazards and controls for the home food preparer, Tech. report, Hospitality Institute of Technology and Management, 2006.

[SSVB97] J. D. Schuman, B. W. Sheldon, J. M. Vandepopuliere, and H. R. Ball, Jr., Immersion heat treatments for inactivation of Salmonella enteritidis with intact eggs, Journal of Applied Microbiology 83 (1997), 438--444.

[STM07] Kritsna Siripon, Ampawan Tansakul, and Gauri S. Mittal, Heat transfer modeling of chicken cooking in hot water, Food Research International 40 (2007), 923--930.

[Thi06] Hervé This, Molecular gastronomy: Exploring the science of flavor, Columbia University Press, New York, 2006.

Footnotes:

¹Sterilization is typically achieved by using a pressure cooker to heat the center of the food to 250°F (121°C) for 2.4 minutes [Sny06]. Sterilized foods are shelf stable, but are grossly overcooked and taste similar to canned foods.

²Shortly before serving, soak in a clean container filled with clean, cold water. Then, wash in a colander under running water to remove and dilute surface microorganisms [Sny06].

³Some countries now require a 6D reduction in Listeria. For convenience, I have included Listeria pasteurization times with some of the recipes in Part II.

⁴ Where I assume that the values of k, ρ, and C_p are normally distributed