Sous-vide (pronounced /su ˈvid/), French for "under vacuum", is a method of cooking that is intended to maintain the integrity of ingredients by heating them for an extended period of time at relatively low temperatures. Food is cooked for a long time, sometimes well over 24 hours. Unlike cooking in a slow cooker, sous-vide cooking uses airtight plastic bags placed in hot water well below boiling point (Usually around 60°C = 140°F).The method was developed by Georges Pralus in the mid-1970s for the Restaurant Troisgros (of Pierre and Michel Troigros) in Roanne, France. He discovered that when cooking foie gras in this manner it kept its original appearance, did not lose excess amounts of fat and had better texture. The method is used in several top-end restaurants under Thomas Keller, Paul Bocuse, Joël Robuchon, Charlie Trotter, and other chefs. Amtrak has used this method of cooking in the dining cars of its long-distance trains, and recently began using the method on its Acela Express trains. Non-professional cooks are also beginning to use vacuum cooking. Botulinum bacteria can grow in food in the absence of oxygen and produce deadly toxin: sous vide cooking must be performed under carefully controlled conditions to avoid botulism poisoning. To help with food safety and taste, relatively expensive water-bath machines (thermal immersion circulator) are used to circulate precisely heated water; differences of even one degree can affect the finished product.In the USA and other English speaking countries, this technique may be known as Cryovacking References^ a b sous-vide. Dictionary.com Unabridged (v 1.1). Random House, Inc. Retrieved on 2007-12-14.^ Under Pressure - New York Times External linksFive-Star Food for 400: It All Starts in the Bag - Washington PostUnder Pressure - New York TimesNewman, Carole M, "Sealed, Signed and delivered", Art Culinaire (2003)Cooking at low temperatures "sous vide"Cooking in a Vacuum