Low-temperature cooking

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Low-temperature cooking is a cooking technique using lower than normal temperature to cook food. Low-temperature refers to the temperature of the cooking medium, not the final temperature at which food may be served. In low-temperature cooking the ingredients are cooked at a temperature between 45 to 85 °C (113 to 185 °F) for a prolonged period of time. Low temperature cooking methods includes sous vide cooking and slow cooking using a slow cooker, but can also be done using a normal oven which has a minimal setting of 70ºC or a combi steamer providing exact temperature control.

Theory[edit]

Low-temperature cooking has been around for hundreds of years; evidence of its usage can be found in indigenous cultures. Samoans and Tongans slow cook meat in large pits for celebrations and ceremonies. However, the technique was not scientifically examined until the 18th century when Benjamin Thompson "described how he had left a joint of meat in a drying oven overnight and was amazed when, the next morning, he found that the meat was tender and fully cooked."[1] Professor Nicholas Kurti from the University of Oxford repeated these experiments in 1969 when he showed that the temperature of Thompson's trial never exceeded 70 degrees Celsius.[1]

Meat is cooked for four reasons — to tenderise it, to provide additional flavours, to kill harmful bacteria, and to kill parasites such as Trichinella spiralis and Diphyllobothrium.[2] While all four can be achieved by cooking a piece of meat at high temperature for a short period of time, it can also be achieved by cooking at low temperature for a long period of time.[3] Each goal is achieved at a different temperature, and takes a different length of time to achieve. There is an inverse relationship between temperature and time; low and slow, or high and fast, with Southern BBQ being an excellent example of low and slow - taking a tough cut of meat and producing pulled pork BBQ by cooking low (at low temperature) and slow (for a long duration).

Tenderisation[edit]

Toughness in meat is derived from several proteins, such as actin, myosin and collagen, that combined form the structure of the muscle tissue. Heating these proteins causes them to denature, or break down into other substances, which in turn changes the structure and texture of meat, usually reducing its toughness and making it more tender. This typically happens between 55 °C and 65 °C (131 °F and 149 °F) over an extended period of time.

Flavour[edit]

Flavours may be enhanced by the Maillard reaction, which combines sugars and amino acids at temperatures above 115 °C (239 °F).[4] A roast meat typically has a brown crust, which is caused by such a reaction and is generally considered desirable. Meat can be cooked at a high heat for a short time browning just the surface, before or after being cooked at low temperature to obtain the benefits of both methods.

Bacteria[edit]

Bacteria are typically killed at temperatures of around 68 °C (154 °F). Most harmful bacteria live on the surface of pieces of meat (assuming the meat has not been ground or shredded before cooking). As a result, for unprocessed steaks or chops of red meat it is usually safe merely to bring the surface temperature of the meat to this temperature and hold it there for a few minutes.[5] See food safety

Gravy[edit]

Since low-temperature cooking reduces the amount of fat rendered out of the meat, producing gravy from the meat may be more difficult. However, gravy may be unnecessary, since the meat is often sufficiently moist when cooked using this technique.

Practice[edit]

A typical process for low-temperature cooking would involve vacuum sealing food in a plastic bag and placing vacuum packaged food in a water bath or steam environment (combi steamer) with precisely controlled temperature for a long duration. The food is then briefly browned, its outside surface temperature exposed to a much higher temperature (e.g., 400 °F), using a roasting pan or even a [blow torch][6] prior to serving. One eccentric variant of low-temperature cooking involves placing the food in a dishwasher.[7]

See also[edit]

References[edit]

  1. ^ a b ."Full on Food: Low Temperature Cooking". BBC. Retrieved 16 May 2012. 
  2. ^ Joel Fuhrman, M.D. (September 12, 2006). "The Cold Truth About Raw Food Diets". DiseaseProof.com. Retrieved 16 May 2012. 
  3. ^ "Low Temperature Cooking". BBC. Retrieved 16 May 2012. 
  4. ^ McGee, Harold (2004). On Food and Cooking. Scribner. p. 779. ISBN 9780684800011. 
  5. ^ "Low Temperature Cooking". BBC. Retrieved 16 May 2012. 
  6. ^ Heston Blumenthal (2006). In Search of Perfection. ISBN 0-7475-8409-5.  (see recipe for cooking steaks)
  7. ^ Riley Woodford (2006). "Dishwasher Salmon". Alaska Department of Fish and Game. Retrieved 2011-03-02. 

External links[edit]