Low-temperature cooking is a cooking technique that usestemperatures in the range of about 60 to 90 °C (140 to 194 °F)[1] for a prolonged time to cook food. Low-temperature cooking methods includesous vide cooking, slow cooking using aslow cooker, cooking in a normal oven which has a minimal setting of about 70 °C (158 °F), and using acombi steamer providing exact temperature control. The traditionalcooking pit also cooks food at low temperature.
Cooking food by a low-temperature method does not necessarily imply that theinternal temperature of the food is lower than by traditional cooking.
In theAmerican South, this style of cooking is sometimes referred to as "low and slow".[2]
Low-temperature cooking has been used for a long time; evidence of its use can be found inindigenous cultures.Samoans andTongans slow-cookmeat in large pits for celebrations and ceremonies. However, the technique was not scientifically examined until the 18th century, whenBenjamin 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."[3] ProfessorNicholas Kurti from the University of Oxford repeated these experiments in 1969, and showed that the temperature of Thompson's trial never exceeded 70 degrees Celsius (158 °F).[3]
Meat is cooked for four reasons: to tenderise it, to provide additional flavours, to kill harmfulbacteria, and to killparasites such asTrichinella spiralis andDiphyllobothrium.[4] All four can be achieved by cooking meat at high temperature for a short time, and by cooking at low temperature for a long time. Each goal is achieved at a different temperature, and takes a different time to achieve. The lower the temperature used, the longer the cooking time. An example of slow, long cooking is Southern pulled pork BBQ.[citation needed]
Toughness in meat is derived from severalproteins, such asactin,myosin andcollagen, 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 takes place between 55 and 65 °C (131 and 149 °F) over an extended period of time.[citation needed]
Flavours may be enhanced by theMaillard reaction, which combinessugars andamino acids at temperatures above 115 °C (239 °F).[5] Meat roasted traditionally in a hot oven has a brown crust which is generally considered desirable, caused by the Maillard reaction. Meat can be cooked at a high temperature for a short time to brown just the surface, before or after being cooked at low temperature, thus obtaining the benefits of both methods.[citation needed]
Bacteria are typically killed at temperatures of around 68 °C (154 °F).[citation needed] Most harmful bacteria live on the surface of pieces of meat which have 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.[3][6] Meat which has been ground needs to be cooked at a temperature and time sufficient to kill bacteria. Poultry such aschicken has a porous texture not visible to the eye, and can harbour pathogens in its interior even if the exterior is heated sufficiently.[7]
Low-temperature cooking reduces the amount of fat and juices, normally used to make gravy, rendered out of the meat. However, when using a plastic bag, little to no evaporation occurs while the meat is cooking, which results in plentiful bag juices.[citation needed]
Sous-vide low-temperature cooking is carried out by vacuum-sealing food in aplastic bag placed in a water bath orcombi steamer with precisely controlled temperature for a long time. The food may then be browned by heating the surfaces to a much higher temperature of perhaps 200 °C (392 °F), using a roasting pan or ablow torch[8] prior to serving. Adishwasher has been used to cook salmon.[9]
Below is the table of minimum coretemperature for different food.
Beef, Pork, Veal, and Lamb: 145 °F (63 °C) with a 3-minute rest time
Ground Meat: 160 °F (71 °C)
Ham, uncooked: 145 °F (63 °C) with a 3-minute rest time
Ham, fully cooked: 140 °F (60 °C) to reheat (caveat:[10])
Poultry: 165 °F (74 °C)
Eggs:
Egg Dishes: 160 °F (71 °C)
Fin Fish: 145 °F (63 °C) or flesh is opaque & separates easily with fork
Shrimp, Lobster, and Crabs: Flesh pearly & opaque
Clams, Oysters, and Mussels: Shells open during cooking
Scallops: Flesh is milky white or opaque and firm
Leftovers and Casseroles: 165 °F (74 °C)[15]