Sous vide

Sous vide cooking is characterized by low-temperature cooking, a longer period of cooking than conventional cooking, a container (such as a plastic bag) that separates the food from its heating environment, and pressurized enclosure using full or partial vacuum. Low-temperature cooking was first described by Benjamin Thompson, Count Rumford in 1799. He used air as the heat-transfer medium in his experiments while attempting to see if he could roast meat in a machine which he had created to dry potatoes. In Thompson's own words, the meat was: "Not merely eatable, but perfectly done, and most singularly well-tasted." Preparation of food under pressure, with or without heat, was developed by American and French engineers in the mid-1960s as an industrial food preservation method. As with Rumford, the researchers learned that the food showed distinctive improvements in flavor and texture. As this method was pioneered, applying pressure to food through vacuum sealing was sometimes called "cryovacking". The pressure notably concentrated the flavors of fruits, even without cooking. The method was adopted by Georges Pralus, a French chef, 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. Another pioneer in sous vide is Bruno Goussault, the French chief scientist of Sterling, Virginia-based food manufacturer Cuisine Solutions. In 1991, he established Centre de Recherche et d'Études pour l'Alimentation (CREA) as the service arm of its parent company, Cuisine Solutions. Due to his research into the effects of temperature on various foods, through CREA, he became well known for training top chefs in the method. He developed the parameters of cooking times and temperatures for various foods. Goussault and Pralus independently worked on development of sous vide in the 1970s and eventually became collaborators. Goussault pioneered the marriage of vacuum sealing with low-temperature cooking. Pralus, considered the father of modern sous vide, cooked at higher temperatures. ==Essential features==

Sealing the food in sturdy plastic bags retains juices and aroma that otherwise would be lost in the process. Placing the packaged food in a water bath, with the temperature set at the desired final cooking temperature of the food, prevents overcooking, because the food cannot get hotter than the bath it is in, as in bain-marie. 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. ==Temperature==

The degree of accuracy and constancy of cooking temperature required varies with the food cooked. In some cases, it is not critical. A piece of fish will cook in 17 to 18 minutes at any temperature from to . Regular cooking times are determined by when the center of the cooked item reaches a few degrees below the targeted temperature. Then heating should be stopped immediately. While the food rests, residual heat will continue to cook it for a while. If the heating continues, the food will be overcooked. The time taken for the center of food to reach the target temperature depends on the initial temperature, the thickness and shape of the food, and the temperature of the bath. ==Limitations==

One limitation of sous vide cooking is that browning (Maillard reactions) happens at 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 many cases, chefs will brown meats and other foods before or after sous vide cooking, using techniques such as torching or searing on an extremely hot pan. This secondary browning is done briefly, and sometimes at higher heat than usually used, so as to affect only the surface of the food and to avoid overcooking the interior. Similarly, the skin of fish can be cooked at high temperatures after the sous vide to make the skin crisp. ==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. Some sous vide fish recipes, for example, are cooked below . People with compromised immunity should never eat food that has not been properly pasteurized. Women eating unpasteurized food while pregnant expose themselves and their fetus to risk and thus may choose to avoid unpasteurized recipes. The degree of danger posed is controversial. Also, some evidence shows that heterocyclic aromatic amines and bisphenol-A migrate from the plastic container into the food in sous vide cooking. ==Uses==

The sous vide method is used in many high-end gourmet restaurants by chefs such as Heston Blumenthal, It has also been used to quickly produce significant quantities of meals for hurricane evacuees. Lower-cost units are now available in the form of a "stick", which has a clip to attach it to the side of the cooking vessel. Sous vide sticks provide a heating element, controller, and motorized impeller. The higher-cost units provide a more precise degree of control over the water temperature. Devices are becoming more user-friendly, with apps affiliated with most of the devices. Apps guide people through the cooking process, with some units having voice-control integration and Wi-Fi interfaces to control the device remotely. ==See also==