This article is about the preparation of food specifically via heat. For a general outline, seeOutline of food preparation. For varied styles of international food, seeCuisine.
Cooking, also known ascookery or professionally as theculinary arts, is the art,science and craft of usingheat to makefood morepalatable,digestible,nutritious, orsafe. Cooking techniques and ingredients vary widely, from grilling food over an openfire, to usingelectric stoves, tobaking in various types ofovens, reflecting local conditions. Cooking is an aspect of all human societies and acultural universal.
Types of cooking also depend on the skill levels and training of thecooks. Cooking is done both by people in their own dwellings and by professional cooks andchefs inrestaurants and other food establishments.
Preparing food with heat or fire is an activity unique tohumans. Archeological evidence of cooking fires from at least 300,000 years ago exists, but some estimate that humans started cooking up to 2 million years ago.[1][2]
The expansion ofagriculture,commerce,trade, andtransportation betweencivilizations in different regions offered cooks many new ingredients. New inventions and technologies, such as the invention ofpottery for holding andboiling ofwater, expanded cooking techniques. Some modern cooks apply advancedscientific techniques to food preparation to further enhance theflavor of the dish served.[3]
In the 17th and 18th centuries, food was a classic marker of identity in Europe. In the 19th-century "Age ofNationalism",cuisine became a defining symbol of national identity.[citation needed]
TheIndustrial Revolution brought mass-production, mass-marketing, and standardization of food. Factories processed, preserved, canned, and packaged a wide variety of foods, and processed cereals quickly became a defining feature of the American breakfast.[16] In the 1920s,freezing methods,cafeterias, andfast food restaurants emerged.
Most ingredients in cooking are derived from livingorganisms. Vegetables, fruits, grains and nuts as well as herbs andspices come from plants, while meat, eggs, and dairy products come from animals. Mushrooms and the yeast used in baking are kinds offungi. Cooks also usewater andminerals such assalt. Cooks can also usewine orspirits.
Naturally occurring ingredients contain various amounts of molecules calledproteins,carbohydrates andfats. They also contain water and minerals. Cooking involves a manipulation of the chemical properties of these molecules.
Carbohydrates include the common sugar,sucrose (table sugar), adisaccharide, and such simple sugars asglucose (made by enzymatic splitting of sucrose) andfructose (from fruit), andstarches from sources such as cereal flour, rice,arrowroot and potato.[17]
The interaction of heat and carbohydrate is complex.Long-chain sugars such asstarch tend to break down into more digestiblesimpler sugars.[18] If the sugars are heated so that all water ofcrystallisation is driven off,caramelization starts, with the sugar undergoing thermal decomposition with the formation ofcarbon, and other breakdown products producingcaramel. Similarly, the heating of sugars and proteins causes theMaillard reaction, a basic flavor-enhancing technique.
Anemulsion of starch with fat or water can, when gently heated, provide thickening to the dish being cooked. InEuropean cooking, a mixture of butter and flour called aroux is used to thicken liquids to make stews or sauces.[19] In Asian cooking, a similar effect is obtained from a mixture of rice orcorn starch and water. These techniques rely on the properties of starches to create simpler mucilaginoussaccharides during cooking, which causes the familiar thickening ofsauces. This thickening will break down, however, under additional heat.
Types of fat includevegetable oils, animal products such as butter andlard, as well as fats from grains, includingmaize andflax oils. Fats are used in a number of ways in cooking and baking. To preparestir fries,grilled cheese orpancakes, the pan or griddle is often coated with fat or oil. Fats are also used as an ingredient in baked goods such ascookies, cakes and pies. Fats can reach temperatures higher than the boiling point of water, and are often used to conduct high heat to other ingredients, such as in frying, deep frying or sautéing. Fats are used to add flavor to food (e.g., butter or bacon fat), prevent food from sticking to pans and create a desirable texture.
Edible animal material, includingmuscle,offal, milk,eggs andegg whites, contains substantial amounts of protein.[24][25][26] Almost all vegetable matter (in particularlegumes andseeds) also includes proteins, although generally in smaller amounts.[27] Mushrooms have high protein content.[28][29] Any of these may be sources ofessential amino acids.[30] Whenproteins are heated they becomedenatured (unfolded) and change texture. In many cases, this causes the structure of the material to become softer or morefriable – meat becomescooked and is more friable and less flexible. In some cases, proteins can form more rigid structures, such as the coagulation ofalbumen in egg whites. The formation of a relatively rigid but flexible matrix from egg white provides an important component in baking cakes, and also underpins many desserts based onmeringue.
Cooking often involves water, and water-based liquids. These can be added in order to immerse the substances being cooked (this is typically done with water,stock or wine). Alternatively, the foods themselves can release water. A favorite method of adding flavor to dishes is to save the liquid for use in otherrecipes. Liquids are so important to cooking that the name of the cooking method used is often based on how the liquid is combined with the food, as insteaming,simmering,boiling,braising andblanching. Heating liquid in an open container results in rapidly increasedevaporation, whichconcentrates the remainingflavor and ingredients; this is a critical component of bothstewing and sauce making.
Vitamins and minerals are required for normalmetabolism; and what the body cannot manufacture itself must come from external sources. Vitamins come from several sources including fresh fruit and vegetables (Vitamin C), carrots,liver (Vitamin A), cereal bran, bread, liver (B vitamins), fish liver oil (Vitamin D) and fresh green vegetables (Vitamin K). Many minerals are also essential in small quantities including iron,calcium,magnesium,sodium chloride andsulfur; and in very small quantities copper,zinc andselenium. The micronutrients, minerals, and vitamins[31] in fruit and vegetables may be destroyed or eluted by cooking. Vitamin C is especially prone to oxidation during cooking and may be completely destroyed by protracted cooking.[32][failed verification] Thebioavailability of some vitamins such asthiamin,vitamin B6,niacin,folate, andcarotenoids are increased with cooking by being freed from the food microstructure.[33] Blanching or steaming vegetables is a way of minimizing vitamin and mineral loss in cooking.[34]
There are many methods of cooking, most of which have been known since antiquity. These include baking, roasting, frying, grilling, barbecuing, smoking, boiling, steaming and braising. A more recent innovation is microwaving. Various methods use differing levels of heat and moisture and vary in cooking time. The method chosen greatly affects the result. Some major hot cooking techniques include:
Steaming works by boiling water continuously, causing it to vaporise into steam; the steam then carries heat to the nearby food, thus cooking the food. By many it is considered a healthy form of cooking, holding nutrients within the vegetable or meat being cooked.
En papillote – The food is put into a pouch and then baked, allowing its own moisture to steam the food.
Smoking
Smoking is the process of flavoring, cooking, or preserving food by exposing it to smoke from burning or smoldering material, most often wood.
As of 2021, over 2.6 billion people cook using open fires or inefficient stoves usingkerosene,biomass, andcoal as fuel.[35][36] These cooking practices use fuels and technologies that produce high levels of household air pollution, causing 3.8 million premature deaths annually. Of these deaths, 27% are frompneumonia, 27% fromischaemic heart disease, 20% fromchronic obstructive pulmonary disease, 18% fromstroke, and 8% fromlung cancer. Women and young children are disproportionately affected, since they spend the most time near the hearth.[37]
Thesterilizing effect of cooking depends on temperature, cooking time, and technique used. Somefood spoilage bacteria such asClostridium botulinum orBacillus cereus can form spores that survive cooking or boiling, which thengerminate and regrow after the food has cooled. This makes it unsafe to reheat cooked food more than once.[40]
Cooking increases the digestibility of many foods which are inedible or poisonous when raw. For example, rawcereal grains are hard to digest, whilekidney beans are toxic when raw or improperly cooked due to the presence ofphytohaemagglutinin, which is inactivated by cooking for at least ten minutes at 100 °C (212 °F).[41]
Food safety depends on the safe preparation, handling, and storage of food. Food spoilage bacteria proliferate in the "Danger zone" temperature range from 40 to 140 °F (4 to 60 °C); therefore, food should not be stored in this temperature range.Washing of hands and surfaces, especially when handling different meats, and keeping raw food separate from cooked food to avoid cross-contamination,[42] are good practices in food preparation.[43] Foods prepared on plastic cutting boards may be less likely to harbor bacteria than wooden ones.[44][45] Washing anddisinfecting cutting boards, especially after use with raw meat, poultry, or seafood, reduces the risk of contamination.[45]
Proponents ofraw foodism argue that cooking food increases the risk of some of the detrimental effects on food or health. They point out that during cooking of vegetables and fruit containingvitamin C, the vitamin elutes into the cooking water and becomes degraded through oxidation. Peeling vegetables can also substantially reduce the vitamin C content, especially in the case of potatoes where most vitamin C is in the skin.[46] However, research has shown that in the specific case ofcarotenoids a greater proportion is absorbed from cooked vegetables than from raw vegetables.[32]
Sulforaphane, aglucosinolate breakdown product, is present in vegetables such asbroccoli, and is mostly destroyed when the vegetable is boiled.[47][48] Although there has been some basic research on howsulforaphane might exert beneficial effects in vivo, there is no high-quality evidence for its efficacy against human diseases.
TheUnited States Department of Agriculture has studied retention data for 16 vitamins, 8 minerals, and alcohol for approximately 290 foods across various cooking methods.[49]
Chicken,pork andbacon-wrappedcorn cooking in abarbecue smoker. Studies show that barbecuing and smoking generate carcinogens.
In a human epidemiological analysis byRichard Doll andRichard Peto in 1981, diet was estimated to cause a large percentage of cancers.[50] Studies suggest that around 32% of cancer deaths may be avoidable by changes to the diet.[51] Some of these cancers may be caused by carcinogens in food generated during the cooking process, although it is often difficult to identify the specific components in diet that serve to increase cancer risk.[52]
Several studies published since 1990 indicate that cooking meat at high temperature createsheterocyclic amines (HCA's), which are thought to increase cancer risk in humans. Researchers at theNational Cancer Institute found that human subjects who ate beef rare or medium-rare had less than one third the risk of stomach cancer than those who ate beef medium-well or well-done.[53] While avoiding meat or eating meat raw may be the only ways to avoid HCA's in meat fully, the National Cancer Institute states that cooking meat below 212 °F (100 °C) creates "negligible amounts" of HCA's. Also,microwaving meat before cooking may reduce HCAs by 90% by reducing the time needed for the meat to be cooked at high heat.[53]Nitrosamines are found in some food, and may be produced by some cooking processes from proteins or from nitrites used as food preservatives; cured meat such as bacon has been found to be carcinogenic, with links to colon cancer.Ascorbate, which is added to cured meat, however, reduces nitrosamine formation.[52][54]
Baking, grilling or broiling food, especially starchy foods, until a toasted crust is formed generates significant concentrations ofacrylamide. This discovery in 2002 led to international health concerns. Subsequent research has however found that it is not likely that the acrylamides in burnt or well-cooked food cause cancer in humans;Cancer Research UK categorizes the idea that burnt food causes cancer as a "myth".[55]
Cooking food at high temperature may createadvanced glycation end-products (AGEs) that are believed to be involved in a number of diseases, including diabetes, chronic kidney disease, cancer and cardiovascular diseases, as well as in ageing. AGEs are a group of compounds that are formed between reducing sugars and amino acids viaMaillard reaction. These compounds impart colors, tastes and smells that are specific to these food, but may also be deleterious to health.[56] Dry heat (e.g. in roasting or grilling) can significantly increase the production of AGEs, as well as food rich in animal protein and fats. The production of AGEs during cooking can be significantly reduced by cooking in water or moist heat, reducing the cooking times and temperatures, as well as by first marinating the meat in acidic ingredients such as lemon juice and vinegar.[57]
The scientific study of cooking has become known as molecular gastronomy. This is a subdiscipline offood science concerning the physical and chemical transformations that occur during cooking.[58]
Important contributions have been made by scientists, chefs and authors such asHervé This (chemist),Nicholas Kurti (physicist),Peter Barham (physicist),Harold McGee (author),Shirley Corriher (biochemist, author),Robert Wolke (chemist, author.) It is different for the application of scientific knowledge to cooking, that is "molecular cooking" (for the technique) or "molecular cuisine" (for a culinary style), for which chefs such as Raymond Blanc, Philippe and Christian Conticini,Ferran Adria,Heston Blumenthal,Pierre Gagnaire (chef).[59]
Chemical processes central to cooking include hydrolysis (in particular beta elimination of pectins, during the thermal treatment of plant tissues), pyrolysis, and glycation reactions wrongly namedMaillard reactions.[60][61]
Cooking foods with heat depends on many factors: thespecific heat of an object,thermal conductivity, and (perhaps most significantly) the difference in temperature between the two objects.Thermal diffusivity is the combination of specific heat, conductivity anddensity that determines how long it will take for the food to reach a certain temperature.[62]
A restaurant kitchen inMunich, Germany (Haxnbauer restaurant)
Home cooking has traditionally been a process carried out informally in a home or around acommunal fire, and can be enjoyed by all members of the family, although in many cultures women bear primary responsibility.[63] Cooking is also often carried out outside of personal quarters, for example at restaurants, or schools.Bakeries were one of the earliest forms of cooking outside the home, and bakeries in the past often offered the cooking of pots of food provided by their customers as an additional service. In the present day, factory food preparation has become common, with many "ready-to-eat" as well as "ready-to-cook" foods being prepared and cooked in factories and home cooks using a mixture ofscratch made, and factory made foods together to make ameal. The nutritional value of including more commercially prepared foods has been found to be inferior to home-made foods.[64] Home-cooked meals tend to be healthier with fewer calories, and lesssaturated fat,cholesterol andsodium on a per calorie basis while providing morefiber,calcium, andiron.[65] The ingredients are also directly sourced, so there is control over authenticity, taste, and nutritional value. The superior nutritional quality of home-cooking could therefore play a role in preventingchronic disease.[66] Cohort studies following the elderly over 10 years show that adults who cook their own meals have significantly lower mortality, even when controlling for confounding variables.[67]
"Home-cooking" may be associated withcomfort food,[68] and some commercially produced foods and restaurant meals are presented through advertising orpackaging as having been "home-cooked", regardless of their actual origin. This trend began in the 1920s and is attributed to people in urban areas of the U.S. wanting homestyle food even though their schedules and smaller kitchens made cooking harder.[69]
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^Pollard, Elizabeth (2015).Worlds Together, Worlds Apart. New York: Norton. p. 13.ISBN978-0-393-92207-3.
^Luke, Kim."Evidence That Human Ancestors Used Fire One Million Years Ago". Retrieved27 October 2013.An international team led by the University of Toronto and Hebrew University has identified the earliest known evidence of the use of fire by human ancestors. Microscopic traces of wood ash, alongside animal bones and stone tools, were found in a layer dated to one million years ago
^Entry for"fat""Fat | Definition of Fat by Merriam-Webster". Archived from the original on 25 July 2020. Retrieved8 December 2023.{{cite web}}: CS1 maint: bot: original URL status unknown (link) in the online Merriam-Webster disctionary, sense 3.2. Accessed on 2020-08-09
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