Sous-vide

Sous-vide cooking

Sous-vide ( /suːˈviːd/; French for "under vacuum")^[1] is a method of cooking food sealed in airtight plastic bags in a water bath for a long time—72 hours is not unusual—at an accurately determined temperature much lower than normally used for cooking, typically around 60 °C or 140 °F. The intention is to cook the item evenly, not overcook the outside while still keeping the inside at the same 'doneness' and to keep the food juicier.

History

The method, first described by Sir Benjamin Thompson (Count Rumford) in 1799, was re-discovered by American and French engineers in the mid-1960s as an industrial food preservation method.^[2] The method was adopted by Georges Pralus in 1974 for the Restaurant Troisgros (of Pierre and Michel Troisgros) in Roanne, France. He discovered that when foie gras was cooked in this manner it kept its original appearance, did not lose excess amounts of fat and had better texture.^[2] Another pioneer in the science of sous-vide is Bruno Goussault, who further researched the effects of temperature on various foods and became well-known for training top chefs in the method. As chief scientist of Alexandria, Virginia-based food manufacturer Cuisine Solutions, Goussault developed the parameters of cooking times and temperatures for different foods.^[2]

Essential features

As may also be done in traditional poaching, sealing the food in sturdy plastic bags keeps in juices and aroma that would otherwise be lost in the process.

The use of temperatures much lower than for conventional cooking is an equally essential feature of sous-vide, resulting in much higher succulence: at these lower temperatures, cell walls in the food do not burst.^[2] In the case of meat cooking, tough collagen in connective tissue can be hydrolyzed into gelatin, without heating the meat's proteins high enough that they denature to a degree that the texture toughens and moisture is wrung out of the meat. In contrast, with the cooking of vegetables, where extreme tenderness or softness is seen as undesirably overcooked, the ability of the sous-vide technique to cook vegetables at a temperature below the boiling point of water allows vegetables to be thoroughly cooked (and Pasteurized, if necessary) while maintaining a firm or somewhat crisp texture. While the cell walls are generally not burst, the depolymerization of the pectic polysaccharides that connect the vegetable's cells together and/or the gelatinization of starch in the vegetable can be achieved without overcooking.^[3]

By placing the food in a water bath whose temperature is set at the desired final cooking temperature of the food, overcooking can be avoided, because the food cannot get hotter than the bath it is in. In conventional high-heat cooking, such as oven roasting or grilling, the food is exposed to heat levels that are much higher than the desired internal cooking temperature; the food must be removed from the high heat prior to its reaching the desired cooking temperature. If the food is removed from the heat too late, overshoot occurs, and if it is removed too early, undercooking results. As a result of precise temperature control of the bath and the fact that the bath temperature is the same as the target cooking temperature, very precise control of cooking can be achieved.^[3] Additionally, temperature, and thus cooking, can be very even throughout the food in sous-vide cooking, even with irregularly shaped or very thick items, given enough time.

From a culinary viewpoint the exclusion of air is secondary, but this has practical importance: it allows cooked food to be stored, still sealed and refrigerated, for considerable times, which is especially useful for the catering industry; and it excludes oxygen from food that requires long cooking and is susceptible to oxidation, e.g., fat on meat, which may become rancid with prolonged exposure to air.^[3]

Prolonged cooking of eggs in the shell at low temperatures, for example, is usually included in the category of sous-vide, although no vacuum is involved.

One limitation of sous-vide cooking is the fact that browning (Maillard reactions) happens at much higher temperatures (above the boiling point of water). The flavors and "crust" texture developed by browning are generally seen as very desirable in the cooking of certain types of meat, such as a steak. The flavors and texture produced by browning cannot be obtained with only the sous-vide technique. In some cases, meats and other foods cooked with the sous-vide technique will be browned either before or after being placed in the water bath, using techniques such as grilling or searing on an extremely hot pan. This secondary browning is done briefly, and sometimes at higher heat than normally used, so as to affect only the surface of the food and to avoid overcooking the interior.^[3]

Modern use

The sous-vide method is used in many high end gourmet restaurants by chefs such as Heston Blumenthal,^[4] Paul Bocuse, Michael Carlson,^[5] Thomas Keller, Ferran Adrià, Joël Robuchon, Alessandro Stratta, Charlie Trotter, Michael Mina and others. Sous-vide has become a common feature on television cooking shows. It has also been used to quickly produce significant quantities of meals for hurricane evacuees.^[6]

Non-professional cooks are also beginning to use sous-vide cooking.^[7] Initially, enthusiasts used laboratory-grade thermal immersion circulators, often bought used on eBay and requiring very careful cleaning, even then not being recommended for kitchen use.^[8] Beginning in 2008, Auber Instruments and Fresh Meals Solutions^[9] made available comparatively inexpensive, yet highly accurate PID controllers with an attached thermocouple probe that could be used to control a commercial rice cooker, slow cooker, electric stock pot, or similar apparatus. In late 2009 the Sous Vide Supreme sous-vide machine (which does not circulate the cooking water) and Addélice swid^[10] immersion circulator, both intended for home use and less expensive than laboratory-standard equipment at a few hundred US dollars, went on sale.

People experimenting with sous-vide techniques have found that the use of an insulated container such as a beer cooler filled with water a little warmer than needed as checked with an accurate thermometer, and ziploc bags with the air sucked out to package the food for cooking, can produce much the same effect for a much lower price.^[11] They recommend adding more insulation in the lid of the cooler to reduce the time spent monitoring and adjusting temperature.

Temperature control

The degree of accuracy and constancy of cooking temperature required varies with the food cooked. In some cases it is not critical; a 15 mm-thick piece of fish will cook in 17 to 18 minutes at any temperature from 44 °C (111 °F) to 61 °C (142 °F);^[3] such food can be cooked in a switched-off slow cooker filled with hot water and a thermometer. But for an egg, which has proteins that coagulate at different temperatures, it is much more critical.^[12]

Cooking times

Times vary considerably. A thin cut of fish may cook in a few minutes. Some otherwise tough cuts of meat, for example beef brisket and short ribs, benefit greatly from very long (48 to 72 hours) sous vide cooking at medium-rare temperatures of around 131 °F (55 °C), but the enzymes in chicken, and particularly fish, turn the food into mush after much shorter times.

Cooking time is often not at all critical, within limits, as the temperature is not high enough to change the nature of the food rapidly.^[13] For example fish, which becomes dry very quickly if cooked conventionally for a little longer than necessary, will remain in perfect condition for a significant time before degrading.

The time and temperature to pasteurise food may be longer than required to make it palatable, although cooking for the longer time will not impair the food. Pasteurisation is not always essential for safety if fresh uncontaminated food is cooked and eaten immediately; fresh raw foods such as sushi and steak tartare are widely eaten without ill effects.

Safety

Food safety is a function of both time and temperature; a temperature usually considered insufficient to render food safe may be perfectly safe if maintained for long enough.^[3]

Clostridium botulinum bacteria can grow in food in the absence of oxygen and produce the deadly botulinum toxin, so sous-vide cooking must be performed under carefully controlled conditions to avoid botulism poisoning.^[14] Generally speaking, food that is heated and served within four hours is considered safe, but meat that is cooked for longer to tenderize must reach a temperature of at least 131 °F (55 °C) within four hours and then be kept there, in order to pasteurize the meat. Pasteurization kills the botulism bacteria, but the possibility of hardy botulism spores surviving and reactivating once cool remains a concern as with many preserved foods, however processed. For that reason, Baldwin's treatise specifies precise chilling requirements for "cook-chill", so that the botulism spores do not have the opportunity to grow or propagate.

Extra precautions need to be taken for food to be eaten by people with compromised immunity. Women eating food cooked sous vide while pregnant may expose risk to themselves and/or their fetus and thus may choose to be more careful than usual.

References

1. ^ "sous-vide". Dictionary.com Unabridged (v 1.1). Random House, Inc. http://dictionary.reference.com/browse/sous-vide. Retrieved 2007-12-14. 
2. ^ ^{a b c d} Amanda Hesser (2005-08-14). "Under Pressure". The New York Times. http://www.nytimes.com/2005/08/14/magazine/14CRYOVAC.html. 
3. ^ ^{a b c d e f} Baldwin: A Practical Guide to Sous Vide Cooking
4. ^ J. Kenji Lopez-Alt (2009-10-26). "Sous-Vide Cooking with Heston Blumenthal". Serious Eats. http://www.seriouseats.com/2009/10/understanding-sous-vide-cooking-heston-blumenthal.html. Retrieved 2010-09-07. 
5. ^ Holly Huges; Charlie O'Malley (2009). "Schwa: Molecular Gastronomy in Chicago #3". Frommer's 500 Places for Food & Wine Lovers. Wiley Publishing, Inc.. ISBN 978-0-470-28775-0. http://books.google.com/books?id=OIClKIFehSAC&pg=PA117. 
6. ^ Candy Sagon (2005-10-05). "Five-Star Food for 400: It All Starts in the Bag". The Washington Post. http://www.washingtonpost.com/wp-dyn/content/article/2005/10/04/AR2005100400271_pf.html. Retrieved 2010-09-07. 
7. ^ Julia Moskin (2009-12-08). "Sous Video Moves From Avant-Garde to the Countertop". The New York Times. http://www.nytimes.com/2009/12/09/dining/09sous.html. Retrieved 2010-09-07. 
8. ^ eBay guide: thermal immersion circulators for cooking
9. ^ "Fresh Meal Solutions". http://Freshmealssolutions.com. 
10. ^ "Addélice swid". http://www.swid.eu/en/. 
11. ^ J. Kenji Lopez-Alt (2010-04-19). "Cook Your Meat in a Beer Cooler: The World's best (and Cheapest) Sous-Video Hack". Serious Eats. http://www.seriouseats.com/2010/04/cook-your-meat-in-a-beer-cooler-the-worlds-best-sous-vide-hack.html. Retrieved 2010-09-07. 
12. ^ Sous vide egg
13. ^ Beginning Sous Vide: Low Temperature Recipes and Techniques for Getting Started at Home
14. ^ Hyytiä-Trees E, Skyttä E, Mokkila M, et al. (2000-01). "Safety evaluation of sous vide-processed products with respect to nonproteolytic Clostridium botulinum by use of challenge studies and predictive microbiological models". Appl. Environ. Microbiol. 66 (1): 223–9. doi:10.1128/AEM.66.1.223-229.2000. PMC 91810. PMID 10618228. http://aem.asm.org/cgi/pmidlookup?view=long&pmid=10618228. 

External links

• Former Microsoft Genius Masters the Culinary Art of Sous-Vide - Wired
• Cooking Sous Vide
• Cooking Sous Vide the DIY Way - Popular Science
• An introduction to sous vide cooking and training courses
• How to build your own Sous Vide rig with off the shelf parts and an Arduino microcontroller.
• Setup Guide to Sous Vide Cooking at Home - Cooking For Engineers
• The sous vide page of the wikiGullet Project - The eGullet Society for Culinary Arts & Letters
• Over 50 Sous Vide recipes and videos, detailed information about functionality, recommended cookery books and much more.