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Cooking

Cooking

Cooking is the act of preparing food for consumption. It encompasses a vast range of methods, tools and combinations of ingredients to improve the flavour and/or digestibility of food. It generally requires the selection, measurement and combining of ingredients in an ordered procedure in an effort to achieve the desired result. Constraints on success include the variability of ingredients, ambient conditions, tools and the skill of the person cooking. The diversity of cooking worldwide is a reflection of the myriad nutritional, aesthetic, agricultural, economic, cultural and religious considerations that impact upon it. Cooking frequently, though not always, involves applying heat in order to chemically transform a food, thus changing its flavor, texture, appearance, and nutritional properties. There is archaeological evidence of cooked foodstuffs (both animal and vegetable) in human settlements dating from the earliest known use of fire.

Effects of cooking

If heating is used, this can disinfect (depending on temperature, cooking time, and technique used) and soften the food. 4 to 60°C (41 to 140°F) is the "food danger zone." Between these temperatures bacteria can grow rapidly. Under the correct conditions bacteria can double in quantity every twenty minutes. The food may not appear any different or spoiled but can be harmful to anyone who ingests it. Meat, poultry, dairy products, and other prepared food must be kept outside of the "food danger zone" to remain safe to eat. Refrigeration and freezing do not kill bacteria, but only slow their growth.

Cooking techniques

Some major hot cooking techniques:
- Baking
- Baking Blind
- Broiling
- FlashBake
- Boiling
- Blanching
- Braising
- Coddling
- Double steaming
- Infusion
- Poaching
- Pressure cooking
- Simmering
- Steaming
- Vacuum flask cooking
- Steeping
- Stewing
- Frying
- Deep frying
- Hot salt frying
- Hot sand frying
- Pan frying
- Pressure frying
- Sautéing
- Stir frying
- Microwaving
- Roasting
- Barbecuing
- Grilling
- Rotisserie
- Searing
- Smoking

Other (cool) preparation techniques

- Brining
- Drying
- Grinding (e.g. sesame seeds to produce tahini), chopping, slicing finely, grating, etc..
- Marinating
- Mincing
- Pickling
- Salting
- Seasoning
- Sprouting

External links

- [http://www.cookbookwiki.com/Category:Cooking_Techniques Cooking_Techniques on CookBookWiki.com]
- [http://www.studentrecipes.com/ Quick and easy recipes for the lazy student]
- [http://www.healthy-quick-meals.com/ Quick healthy recipes]
- [http://www.healthdiaries.com/eatthis/ Healthy Recipes]
- [http://www.spanishliquidgold.com/search.php?q=cooking+classes Cooking classes]
- [http://www.momslilgreentin.com Family Recipes]
- [http://www.gti.net/mocolib1/kid/food1.html Culinary history timeline]
- [http://www.elook.org/recipes/ Recipes]
- [http://www.foodgeeks.com/recipes/ Foodgeeks.com Recipes]
- [http://www.visualrecipes.com Visual Recipes]
- [http://cooking.investitor.net/index.htm Cooking books]
- [http://www.mediterrasian.com/delicious_recipes.htm Mediterranean and Asian recipes]
- [http://www.pygmies.info/food.html African Pygmies cooking] Food preparation in the rain forest
- [http://www.ratemycookingkungfu.com/ Photos of home cooking]
- [http://www.realcajunrecipes.com/ RealCajunRecipes.com - includes Photo Album of Cajun Cooking]
- [http://www.turkishcookbook.com Binnur's Turkish Cookbook] Delicious, healthy and easy-to-make Turkish recipes.
- [http://www.goosto.com Goosto.com] Recipes Search Engine.
- [http://www.yummycrockpotrecipes.com YummyCrockPotRecipes.com Recipes]
- [http://www.foodtv.com FoodTV.com: Extensive Online Recipe Collection from the Food Network]
- [http://www.mexican-barbecue-recipes.com/wikipedia.html Mexican & Barbecue Recipes] Tex-Mex, grilling, and smoked fish.
- [http://www.findmearecipe.com Find Me a Recipe] Searchable database of over 100,000 recipes.
- [http://gourmetfood.about.com Gourmet Cooking, Recipes, & Techniques]
- [http://www.culinarychef.com CulinaryChef.com] An award-winning culinary source for the family, professional cooks, culinary chefs, and for those who enjoy fine eating since 1999. Category:Cooking Category:Food and drink Category:Hobbies Category:Survival skills ja:調理 simple:Cooking

Food

Food is any substance that can be consumed, including liquid drinks. Food is the main source of energy and of nutrition for animals, and is usually of animal or plant origin. The study of food is called food science. In English, the term food is often used metaphorically or figuratively, as in food for thought. Food can also be a system of communication, a collection of images, a protocol of usages, situations, and behavior. Food is what brings the memory of our past into our contemporary life.

Legal definition

Western food law defines four categories of object as food:
- any substance or product, whether processed, partially processed or unprocessed, intended to be, or reasonably expected to be ingested by humans whether of nutritional value or not;
- water and other drinks;
- chewing gum;
- articles and substances used as an ingredient or component in the preparation of food. Links to official legal definitions of food:
- [http://www.fda.gov/opacom/laws/fdcact/fdcact1.htm US federal definition of food]
- [http://www.legislation.hmso.gov.uk/acts/acts1990/Ukpga_19900016_en_2.htm#mdiv1 UK definition of food]
- [http://europa.eu.int/smartapi/cgi/sga_doc?smartapi!celexapi!prod!CELEXnumdoc&lg=EN&numdoc=32002R0178&model=guichett EU definition of food]

Human eating habits

Historical development

Humans are commonly believed to be omnivorous animals that can consume both plant and animal products. Evidence suggests that early Homo Sapiens employed Hunter-gatherer as their primary means of food collection. This involves combining stationary plant and fungal food sources (such as fruits, grains, roots, and mushrooms) with mobile animals which must be hunted and killed in order to be consumed. Additionally, it is believed that humans have used fire to prepare food prior to eating since their divergence from Homo erectus, possibly even earlier. At least ten thousand years ago, humans developed agriculture, which has Timeline of agriculture and food and altered the kind of food people eat. This has led to a variety of important historical consequences, such as increased [[population]], the development of [[cities, and the wider spread of infectious diseases. The types of food consumed, and the way in which they are prepared has varied widely by time, location, and culture.

Meals

A portion of food or the act of eating a portion of food is considered a meal. Often named and patterned, meals play a role in an important social occasion, such as the celebration of many key cultural and religious festivals. A meal can be used as means for feeding a single individual or shared and eaten simultaneously by two or more people. The number of meals consumed by individuals in a day, their size, composition, when and how they are prepared and eaten varies greatly around the world. This diversity can be attributed to a number of local factors, including climate, ecology, economy, cultural traditions and industrialisation. In societies where the availability of food has risen above subsistence levels and beyond staple foods, meals are also sold pre-prepared for immediate consumption in restaurants and other similar retail premises. Food eaten in smaller quantities between the culturally normative meals is regarded as snack food. :See also: Appetite, Buddhist cuisine, Eucharist, Fast food, Fasting, Gault Millau restaurant guide, Halaal, I-tal, Kashrut, Michelin restaurant guide, Muslim dietary laws, Potluck, Totemism.

Food production or acquisition

Food is traditionally obtained through farming, ranching, and fishing, with hunting, foraging and other methods of subsistence locally important for some populations, but minor for others. In the modern era in developed nations, food supply is increasingly dependent upon agriculture, industrial farming, aquaculture and fish farming techniques. These techniques aim to maximize the amount of food produced while minimizing the cost. The techniques include a reliance on mechanized tools, from the threshing machine and seed drill, to the tractor and combine. Developed tools have been combined with the use of pesticides to promote high crop yields and to combat insects or mammals which reduce yield. More recently, there has been a growing trend towards more Sustainable agricultural practices. This approach - which is partly fuelled by consumer demand - encourages biodiversity, local self-reliance and Organic farming methods. Major influences on food production are international policy, e.g. the World Trade Organization and Common Agricultural Policy, national government policy or law and war. Food for livestock is fodder and traditionally comprises hay or grain. :See also: mariculture, horticulture, agribusiness, gardening. gardening

From plants

- Seeds
- Cereals from grasses, including barley, maize, oats, rice, rye, and wheat
- Cereals from non-grasses, including buckwheat, amaranth, and quinoa
- Legumes, including beans, peas, and lentils
- Nuts, including coconuts, almonds, and pine nuts
- Oilseeds, including sesame, sunflower, and hemp
- Vegetables (see also list of vegetables)
- Root vegetables, including potatoes, cassava, and turnips
- Leaf vegetables, including amaranth, spinach, and kale
- Sea vegetables, including dulse, kombu, and dabberlocks
- Stem vegetables, including bamboo shoots, nopales, and asparagus
- inflorescence vegetables, including globe artichokes, broccoli, and daylilies
- Fruit vegetables, including pumpkin, okra, and eggplant
- Fruits (see also list of fruits)
- Herbs and spices (see also list of herbs and spices) list of herbs and spices

From animals

- Dairy products, including milk
- Eggs, including roe and caviar
- Insects, including honey
- Meat, including beef, frogs' legs, goat, horse, kangaroo, lamb, mutton, pork, veal, rodents, human (i.e. cannibalism)
- Offal, including blood
- Poultry, including chicken, turkey, duck, goose, pigeon or dove, ostrich, emu, guinea fowl, pheasant, quail
- Seafood, including finfish such as salmon and tilapia, and shellfish such as mollusks and crustaceans
- Snails
- Game, this includes all animals hunted for food.

From neither animals or plants

- Salt
- Mushrooms, which are a type of fungi
- Seaweed, which is a protist
- Water, including mineral water and spring (water)

Food preparation

spring (water) While some food can be eaten without preparation, many foods undergo some form of preparation for reasons of safety, palatability, or flavor. At the simplest level this may involve washing, cutting, trimming or adding other foods or ingredients, such as spices. It may also involve mixing, heating or cooling, pressure cooking, fermentation, or combination with other food. Most food preparation takes place in a kitchen. The preparation of animal-based food will usually involve slaughter, evisceration, hanging, portioning and rendering. :See also: Barbecue, Eating utensils, Frankfurt kitchen, Hangi, Oven, Microwave oven, Refrigeration, Food preparation utensils.

Food manufacture

Early food processing techniques were limited by the available food preservation, packaging and transportation. Early food processing mainly involved salting, curing, curdling, drying, pickling and smoking. An early processed food product was cheese. During the industrialisation era in the 19th century, food manufacturing arose. This development took advantage of new mass markets and emerging new technology, such as milling, preservation, packaging and labelling and transportation. It brought the advantages of pre-prepared time saving food to the bulk of ordinary people who did not employ domestic servants. At the start of the 21st century, a two-tier structure has arisen, with a few international food processing giants controlling a wide range of well known food brands; with a populous number of small local or national food processing companies. :See also: Best before, Canning, Coloring, Food quality, Snap freezing, Additives, Flavoring, Enzymes, Genetically modified food, Pasteurization, Shelf-life, Ultra-high temperature processing.

Types of manufactured food

- Drinks: beer, juice, soft drink, squash, wine.
- Bread is a staple food for many nations, being made of risen dough of wheat or other cereals.
- Cakes and cookies
- Cheese is a curdled milk product, of which many varieties exist.
- Dessert is a course, usually sweet, and generally served after the main course, e.g. Ice cream.
- French fries, Chips
- Functional food
- Jam and Jelly
- Pasta
- Pie
- Pizza
- Processed meats
- Sandwiches
- Salad
- Sauce
- Sausage

Food trade

Food is now traded on a global basis. The variety and availability of food is no longer restricted by the diversity of locally grown food or the limitations of the local growing season. Between 1961 and 1999 there has been a 400% increase in worldwide food exports. Some countries are now economically dependent on food exports, which in some cases account for over 80% of all exports. In 1994 trade liberalisation began when over 100 countries became signatories to the Uruguay Round of the General Agreement on Tariffs and Trade which included an agreement to reduce subsidies paid to farmers. This is underpinned by the WTO enforcement of agricultural subsidy, tariffs, import quotas and settlement of trade disputes that cannot be bilaterally resolved. Where trade barriers are raised on the disputed grounds of public health and safety, the WTO refer the dispute to the Codex Alimentarius Commission, which was founded in 1962 by the United Nations Food and Agriculture Organization and the World Health Organization.

Food retailing

World Health Organization The sale of surplus food traditionally took place once a week when farmers took their wares on market day, into the local village market place. Here food was sold to grocers for sale in their local shops for purchase by local people. With the onset of industrialisation, and the development of the food processing industry, a wider range of food could be sold and distributed in distant locations. Typically early grocery shops would be counter-based shops, in which purchasers told the shop-keeper what they wanted, so that the shop-keeper could get it for them. In the 20th century supermarkets were born. Supermarkets brought with them a self-service approach to shopping using shopping carts (or Trollies in Commonwealth English) and were able to offer quality food at lower cost, through economies of scale and reduced staffing costs. This was sometimes known as 'pile it high' In the latter part of the 20th century, this has been further revolutionised by the development of vast warehouse sized out-of-town supermarkets, selling an extraordinarily wide range of food from around the world. Unlike food processors, food retailing is a two-tier market in which a small number of very large companies control a large proportion of supermarkets. The supermarket giants wield great purchasing power over farmers and processors, and strong influence over consumers. Nevertheless, in 2000 only 19% of all US consumer expenditure spent on food went to farmers. Recent technological innovations such as point of sale technology - barcodes. This allows ordering of goods and food to be driven by actual sales.

Food sufficiency

Food deprivation leads to malnutrition and ultimately starvation. This is often connected with famine, which involves the absence of food in entire communities. This can have a devastating and widespread effect on human health and mortality. In 2003 it was estimated that each year, 40 million people die of hunger worldwide. Rationing is sometimes used to distribute food in times of shortage, most notably during times of war. Food deprivation is regarded as a deficit need in Maslow's hierarchy of needs and is measured using famine scales.

Food aid

Food aid can benefit people suffering from a shortage of food. Conversely, badly managed food aid can cause problems by disrupting local markets, depressing crop prices and discouraging food production. Its provision, or threatened withdrawal, is sometimes used as a political tool to influence the politics of the destination country. International efforts to distribute food to the neediest countries are co-ordinated by the World Food Programme. :See also: Fair trade, food security.

Food safety

Foodborne illness, commonly called "food poisoning," is caused by bacteria, toxins, viruses and prions. Food poisoning has been recognised as a disease of man since as early as Hippocrates. Murder by food poisoning was used during the Roman Empire. In the Middle Ages all Royal Courts had food tasters. The sale of rancid, contaminated or adulterated food was commonplace until introduction of hygiene, refrigeration, and vermin controls in the 19th century. Discovery of techniques for killing bacteria using heat and other microbiological studies by scientists such as Louis Pasteur contributed to the modern sanitation standards that we enjoy today. This was further underpinned by the work of Justus von Liebig whose work led to the development of modern food storage and food preservation methods. The two most common factors leading to cases of bacterial foodborne illness are cross-contamination of ready-to-eat food from other uncooked foods and improper temperature control. Less commonly, acute adverse reactions can also occur if chemical contamination of food occurs, for example from improper storage, or use of non-food grade soaps and disinfectants. Food can also be adulterated by a very wide range of articles (known as 'foreign bodies') during farming, manufacture, cooking, packaging, distribution or sale. For example, pests (or their feces), hairs, cigarette butts, wood chips, metal shards, plasters etc. It is possible for certain types of food to become contaminated if stored or presented in an unsafe container, such as a ceramic pot with lead-based glaze. Understanding of the causes of food-borne-illnesses and more systematic techniques for their elimination has led to the development of commercial systems such as HACCP which can, if properly implemented, identify and eliminate many, but not all, possible risks. HACCP is well suited to identifying and controlling these potential food safety risks.

Food allergies

Some people have food allergies or sensitivities to foods which are otherwise wholesome to the majority of people. The amount of the food substance required to provoke a reaction in a susceptible individual can be minute. For instance, tiny amounts of food in the air, too minute to be smelled, have been known to provoke lethal reactions in sufficiently sensitive individuals. In theory, any food may provoke a reaction, however, this most commonly involves gluten, corn, shellfish (mollusks), peanuts, and soy. Most patients present with diarrhea after ingesting certain foodstuffs, skin symptoms (rashes), bloating, vomiting and regurgitation. The digestive complaints usually develop within half an hour of ingesting the allergen. Rarely, food allergy can lead to anaphylactic shock: hypotension (low blood pressure) and loss of consciousness. This is a medical emergency. An allergen associated with this type of reaction is peanut, although latex products can induce similar reactions. Initial treatment is with epinephrine (adrenaline), often carried by known patients in the form of an Epi-pen. Food allergy is thought to develop easier in patients with the atopic syndrome, a very common combination of diseases: allergic rhinitis and conjunctivitis, eczema and asthma. The syndrome has a strong inherited component; a family history of these diseases can be indicative of the atopic syndrome.

Dietary habits

Dietary habits play a significant role in the health and mortality of all humans. For example:
- Eating disorders are a group of mental disorders that interfere with normal food consumption. They often affect people with a negative body image;
- 13% of the world's population suffer from Iodine deficiency;
- In 2003 it was estimated that vitamin A deficiency causes blindness in up to 500,000 children each year;
- Vitamin C deficiency results in scurvy;
- Calcium, Vitamin D and Phosphorus are inter-related. The consumption of each may affect the absorption of the others.
- Kwashiorkor and marasmus are childhood disorders caused by lack of dietary protein.
- Obesity, a serious problem in the western world, leads to higher chances of developing heart disease, diabetes, and many other diseases. Concerns about foodborne illness have long influenced diet. Traditionally humans have learned to avoid foods that induce acute illness. Some believe that this is the underlying rationale behind some traditional religious dietary requirements. Additionally, many people choose to forgo food from animal sources to varying degrees; see vegetarianism, veganism, fruitarianism, living foods diet, and raw foodism. The nutrient content of diets in industrialised countries contain more animal fat, sugar, energy, alcohol and less dietary fiber, carbohydrates and antioxidants. Contemporary changes to work, family and exercise patterns, together with concerns about the effect of nutrition and overeating on human health and mortality are all having an effect on traditional eating habits. Physicians and alternative medicine practitioners may recommend changes to diet as part of their recommendations for treatment. More recently, dietary habits have been influenced by the concerns that some people have about the chronic impact on health that arise through the consumption of genetically modified food. Further concerns about the impact of industrial farming on animal welfare, human health and the environment are also having an effect on contemporary human dietary habits. This has led to the emergence of a counterculture with a preference for organic and local food. :See also: Food faddism, Health claims on food labels, list of diets, Slow Food.

Nutrients in food

- Calcium
- Carbohydrate
- Essential amino acids
- Fat
- Iron
- Minerals
- Phytochemicals, including anti-oxidants, enzymes, bio-flavinoids
- Potassium
- Protein
- Sodium
- Starch
- Vitamins
- Water Category:Nutrition Category:Biology

Fire

Fire is a form of combustion. Linguistically, the word fire refers to the combination of the brilliant glow and large amount of heat released during a rapid, self-sustaining burning of combustible fuel. Technically, fire is not a state of matter; it is an exothermic oxidation process by which heat and light energy are given out. Fire starts when a fuel with adequate oxygen supply is subjected to enough heat, and it is sustained by the further release of heat energy in the process, as well as a continuous supply of oxygen and combustible fuel. A match or lighter is usually used to start a fire (which can then propagate to other combustibles) because matches and lighters are designed with materials of low burning point. Fire is extinguished when one or more of heat, oxygen, and fuel is removed. Flames can conduct electricity, as a small portion of any fire is ionized. This has been demonstrated in the laboratory and also in large wildfires that occur in the vicinity of power lines.

Controlling fire

wildfire wildfire Controlling fire for the purposes of providing heat and light was one of humankind's first great achievements. The ability of fire to generate heat and light made possible migration to colder climates and enabled people to cook food — a decisive step in the perennial fight against disease. Smoke signals were an early use of fire for communication, and fire soon enabled advancements in metallurgy such as smelting and forging. Archaeology indicates that ancestors of modern humans such as Homo erectus seem to have been using controlled fire as early as some 790,000 years ago. The Cradle of Humankind site has evidence for controlled fire 1 million years ago. By the time of the Neolithic introduction of grain based agriculture, people the world over used fire as a tool in landscape management. These fires were typically controlled "cool fires," as opposed to uncontrolled "hot fires" that damage the soil. Such hot fires destroy plants and animals, and endanger communities. All too often this is a problem in the forests of today where traditional burning is prevented in order to encourage the growth of timber crops. Cool fires are generally conducted in the spring and fall. They clear undergrowth, burning up biomass that could trigger a hot fire should it get too dense. They provide a greater variety of environments, which encourages game and plant diversity. For humans, they make dense, impassable forests traversable. Today, the applications of fire are numerous. In its broadest sense, fire is used by nearly every human being on earth in a controlled setting every day. Owners of internal combustion vehicles use fire every time they drive. Thermal power stations provide electricity for a large percentage of humanity. However, fire is also used more directly; many nomadic peoples still use fire for cooking. It is also used for smoking, and as a weapon. In fact, the use of fire by militaries has a long history up to the present day. Homer detailed its use by Greek commandoes who hid in a wooden horse to burn Troy during the Trojan war. Later the Byzantine fleet (late Romans) used Greek Fire to attack ships and men. In the Vietnam War, the Americans dropped a modern version, Napalm, from the air. More recently many villages were burned during the Rwandan Genocide. Aerial bombing of cities, including firebombing (using incendiary bombs) was also frequently used during World War II. See also :Category:Incendiary weapons. Molotov cocktails are in common use as well.

Fire and religion

Fires and burning have often been used in religious rites and symbolism, as the smoke of the fire disperses into the heavens. Fire is one of the four classical elements, as well as one of the five Chinese elements. In Hinduism fire is one of five sacred elements of which all living creatures are comprised and is considered an eternal witness essential to sacred religious ceremonies. In Christianity, fire is a symbol of the Holy Ghost and is often used in descriptions of Hell. Fire is a symbol of Ahura Mazda, or God, of the Zoroastrian religion. A Zoroastrian church is known as a Fire Temple. Fire is also an important part of Calcination, the fire operation in the art of alchemy. In Greek mythology, Prometheus is the Titan chiefly honored for stealing fire from the gods in the stalk of a fennel plant and giving it to mortals for their use. In Judaism fire also has great significance, candles are lit to usher in holidays and to separate Shabbat from the rest of the week, as well as to remember the dead; another important fire symbol is the Eternal Flame, which was a fire kept in the First and Second Temple was never supposed to go out. Fire worship can also relate to Sun worship, especially as the sun viewed as the most expressive and emphatic exhibition of beneficent divine power.

Fire as a power source

Fire has supplied much of the energy which has helped humans since ancient times, from the wood fires which served many prehistoric purposes to the oil, gas and coal power stations of today which supplies the vast majority of the world's electricity (nearly 80%¹). Mexico is typical with thermal energy providing 76% of all energy². The burning of wood is often the first association to the word "fire". It is common in a developing country for wood to be the primary energy source as well. For instance, in Africa, 65% of the energy used comes from the burning of biomass³. What is less obvious is that wood burning power stations are less environmentally destructive than the fired oil power station in two major respects. E.ON UK is soon to build a 44 megawatt wood fired power station in Britain for these reasons, as reported in the Guardian newspaper in October 2005⁴: first, wood is a renewable resource, especially if trees are grown in a modern, sustainable way. Second, the carbon dioxide emissions are negligible because no more carbon dioxide can be produced by burning than would be produced by the natural rotting of wood. Thus, over a 100-year timescale, the effect is carbon-neutral⁵. It is also claimed that this power station will be more efficient than coal: accelerants can be used to spread fire faster or have it burn hotter. The fire in a power station is used to heat water, creating steam that drives turbines. The turbines are linked to an electrical generator.

Uncontrolled fire

electrical generator The self-sustaining nature of fire makes it extremely dangerous if uncontrolled. Fire can consume structures and forests and can severely injure or kill living things through burns or smoke inhalation. Structure fires can be started by cooking accidents, electrical faults, fuel leaks, children playing with lighters and/or matches, and accidents involving candles and cigarettes. Fire can propagate rapidly to other structures, especially where proper building standards are not met. Purposefully starting destructive fires constitutes arson and is a criminal offense in most jurisdictions. The destructive capacity of fire has led most municipalities to offer fire fighting services to quickly extinguish fires. Trained firefighters use fire trucks, fire hydrants, and an array of other equipment to combat the spread of fires. Municipal buildings such as schools and government buildings often conduct fire drills to inform and prepare citizens on how to react to a building fire. Outside of urban settings, wildfires can consume large areas of forest and brush and often damage nearby settlements. There are many different classification systems used for uncontrolled fires; in Europe and Australasia six groups are used:
- Class A: Fires that involve flammable solids such as wood, cloth, rubber, paper, and some types of plastics.
- Class B: Fires that involve flammable liquids or liquefiable solids such as petrol/gasoline, oil, paint, some waxes & plastics, but not cooking fats or oils.
- Class C: Fires that involve flammable gases, such as natural gas, hydrogen, propane, butane.
- Class D: Fires that involve combustible metals, such as sodium, magnesium, and potassium.
- Shock Risk (formerly known as Class E): Fires that involve any of the materials found in Class A and B fires, but with the introduction of an electrical appliances, wiring, or other electrically energized objects in the vicinity of the fire, with a resultant electrical shock risk if a conductive agent is used to control the fire.
- Class F: Fires involving cooking fats and oils. The high temperature of the oils when on fire far exceeds that of other flammable liquids making normal extinguishing agents ineffective. conductive In the U.S., fires are generally classified into four groups: A, B, C, and D.
- Class A: Fires that involve wood, cloth, rubber, paper, and some types of plastics.
- Class B: Fires that involve gasoline, oil, paint, natural and propane gases, and flammable liquids, gases, and greases.
- Class C: Fires that involve any of the materials found in Class A and B fires, but with the introduction of an electrical appliances, wiring, or other electrically energized objects in the vicinity of the fire.
- Class D: Fires that involve combustible metals, such as sodium, magnesium, and potassium. A fifth group, Class K, is sometimes added. It refers to fires involving large amounts of grease or oil. Although, by definition, Class K is a subclass of Class B, the special characteristics of these types of fires are considered important enough to recognize. U.S. iron.]]

Science of fire

A flame is a self-sustaining oxidizing chemical reaction producing energy and ionized gas (plasma). It consists of reacting gases emitting visible and infrared light, the frequency spectrum of which is dependent on the chemical composition of the burning elements and intermediate reaction products. In many cases such as burning organic matter like wood or incomplete combustion of gas, incandescent solid particles (soot) produce the familiar red-orange 'fire' color light. This light has a continuous spectrum. Complete combustion of gas has a dim blue color due to the emission of single wavelength radiations from various electron transitions in the excited molecules formed in the flame. Usually oxygen is involved, but hydrogen burning in chlorine produces a flame as well, producing toxic hydrogen chloride (HCl). Other possible combinations producing flames (amongst many more) are fluorine and hydrogen or hydrazine and nitrogen tetroxide. The glow of a flame is somewhat complex, due to a mix of black-body radiation emitted from soot, gas, and fuel particles (though the soot particles are too small to behave like perfect blackbodies), and from photon emission by de-excited atoms and molecules in the gases. Much of the radiation is emitted in the visible and infrared bands. The color depends on temperature for the black-body radiation, and chemical makeup for the emission spectra. emission spectra

References

- [http://www.iea.org/statlist/index.htm "Share of Total Primary Energy Supply", 2002; International Energy Agency]
- [http://www.geni.org/globalenergy/library/national_energy_grid/mexico/index.shtml "Mexico Grid Summary", 2000; Global Energy Network Institute]; thermal energy defined as oil, gas and coal
- [http://www.eia.doe.gov/emeu/cabs/archives/africa/chapter3.html "Energy in Africa - Chapter 3"], US Energy information administration
- [http://www.guardian.co.uk/science/story/0,3605,1592854,00.html "How Can Burning Wood Help Reduce Global Warming"], The Guardian
- [http://www.straightdope.com/columns/021122.html The Straight Dope: What exactly is fire?]. Adams, C.(2002).Retrieved Dec. 19, 2004.
- Dave Reay, "Climate Change Begins at Home"

External links

- [http://www.straightdope.com/columns/021122.html What exactly is fire?] (from The Straight Dope)
- [http://news.bbc.co.uk/1/hi/sci/tech/3670017.stm Early human fire mastery revealed] BBC article on archeological discoveries
- [http://www.northmason.wednet.edu/NMHSonline/student_gallery/fire/pg19_candleflame.html Parts of a candle flame]
- [http://microgravity.grc.nasa.gov/combustion/cfm/cfm_index.htm Flames in microgravity]
- [http://science.nasa.gov/headlines/y2000/ast12may_1.htm Spiral flames in microgravity]
- [http://www.moebuildingcontrol.co.uk moebuildingcontrol.co.uk - UK Guidance on fire safety codes and fire engineering] Category:Firefighting Category:Chemistry ja:火 ko:불 simple:Fire

Blind-baking

The term blind-baking (sometimes called "pre-baking") refers to the process of baking a pie crust or other pastry without the filling. Generally, the pie crust is lined with tin foil or parchment paper, then filled with dried peas, lentils, beans or other pulses, so that it will keep its shape when baking. (Metal or ceramic pie weights are also used.) After the pie crust is done, the pulses are replaced with the proper filling. Blind-baking is necessary if the pie filling can not be baked as long as the crust requires, or if the filling of the pie would make the crust too soggy if added immediately. Category:Cooking techniques

FlashBake

FlashBake is a high tech cooking technology invented in 1993. A company (Quadlux, Inc. from Fremont, CA, USA) made an oven that cooks with intense infrared and visible light radiation. It can cook like a regular oven with a speed close to that of a microwave oven. This technology is not popular in the home market due to the high price. FlashBake is a registered trademark. This patented technology was licensed to various restaurant equipment suppliers, such as Wolf Stoves and Vulcan-Hart. Other licensees include home appliance manufacturer GE for their Advantium line of oven, and Bosch & Siemens in Europe. Amana developed their own WAVE ovens after failure to license the technology from Quadlux. Amana later lost in a law suit with Quadlux regarding this dispute. Some high end products still use the technology, but Quadlux ended production on 1st July 2000 because of production difficulties with the contract manufacturer Watertown Metal Products. They ceased research and development and dropped to a staff of four. It is unclear as to whether they are still in business.

Blanching

Blanching is a cooking term that describes a process of food preparation wherein the food substance is rapidly plunged into boiling water and then removed after a brief, timed interval and then plunged into iced water or placed under cold running water. Blanching rapidly heats and then cools the food. This allows the food, usually fruits and vegetables, to firm up and makes the food's natural flavour more pronounced, and is often a preparative technique for freezing food. Blanching is also an effective method of loosening the skin on fruits or nuts that one may wish to peel, such as tomatoes, plums, peaches, or almonds. In addition, blanching enhances the color of some (particularly green) ingredients. Steam blanching is also used to neutralise bacteria and enzymes present in foods so that they may be processed and gain a greater shelf life, such as peanuts. Blanching can also describe deep frying in oil at a lower temperature as with the initial cooking of French fries.

External links

- http://www.uga.edu/nchfp/how/freeze/blanching.html National Center for Home Food Preservation - Blanching Category:Cooking techniques

Coddling

In cooking, to coddle food is to heat it in water kept just below the boiling point. The eggs added to a Caesar salad should ideally be coddled. However, coddled eggs are in actual fact still raw and eggs prepared in this way present a salmonella risk. Cooking techniques

Infusion

- An infusion is a beverage made by steeping a flavoring substance in hot or boiling water. Infusions include coffee, tea and tisanes. Infusions can also be made in another substance, such as alcohol or vinegar, instead of water.
- In medicine an infusion is a treatment in which a patient is attached to a device (a drip) that constantly delivers a liquid into the bloodstream. See route of administration for some further details.
- An infusion in the world of aromatherapy refers to two different types or infusions of herbs, flowers, berries, etc. being "infused" or placed in oil. There are short-term infusions which are most popularly used and sold on the open market today. These short-term infusions are made anywhere from 24 hours to just under 3 weeks. Then the herb/botanical is removed from the oil and the oil is used in the many formulas that call for short-term infused oils. Long-term infused oils are made in the same way as the short-term infusions except that these infusions are allowed to set for a minimum of one year or longer before opening in order to have a more concentrated infused oil that is used similar to an essential oil by the drop rather than by the ounce as one would use a short-term infused oil. Long-term infused oils are prized for their vibrant colors, concentration, and their ability to be used with or without essential oils as well as their long shelf life. The first use of infused oils is lost in the mists of history and these infused oils precede the use of essential oils by thousands of years. The first essential oils being made in the 10th century by an Arab chemist, Avicennia. Infusions were the oils that the common man or woman used in daily life. Today they are just now beginning to be researched again. Because they are not able to be patented, there has been very little research done in this area of infusions.
- In other contexts, an infusion can mean the introduction of a modifying quality or element. Thus it could be used to describe the addition of new subject matter into a curriculum, or the addition of talented individuals into an organization.
- Infusion is an Australian dance-music act.
- Infusion Development is a software consulting company and author of the CodeNotes book series.
- A recognized form of Christian baptism (pouring over the head).

Poaching (cooking)

Poaching is the process of gently simmering food in liquid, generally water, stock or wine. Poaching is particularly suitable for fragile food, such as eggs, poultry, fish and fruit, which might easily fall apart or dry out. For this reason, it is important to keep the heat low and to keep the poaching time to a bare minimum, which will also preserve the flavour of the food. Eggs are generally poached in water, fish in white wine, poultry in stock and fruit in red wine.

External links

- [http://forums.egullet.com/index.php?showtopic=36989 Tips and Tricks for poaching eggs] Category:Cooking techniques Poaching an egg without its shell can also be done in a small receptacle placed over boiling water. (From Webster's New World College Dictionary, Fourth Edition)

Pressure cooking

:Pressure cooker redirects here. For the 1997 movie, see Pressurecooker. Pressure cooking is a method of cooking in a sealed vessel that does not permit air or liquids to escape below a preset pressure. Because water's boiling point increases as the pressure increases, the pressure built up inside the cooker allows the liquid in the pot to rise to a temperature higher than 100 °C (212 °F) before boiling. The higher temperature causes the food to cook faster. Cooking times can be reduced by a factor of three or four. For example, shredded cabbage is cooked in one minute, fresh green beans take about five, small to medium-sized potatoes (up to 200 g) may be ready in five minutes or so and a whole chicken takes no more than twenty-five minutes. It is often used to simulate the effects of long braising or simmering in shorter periods of time. A safety valve releases steam when the pressure exceeds the safety limit for the cooker; usually the steam pressure lifts a weighted stopper allowing excess pressure to escape. There is usually a backup pressure release mechanism, in the form of a hole in the lid blocked by a plug of low melting-point alloy. If internal temperature (and hence pressure) gets too high, the metal plug will melt, resulting in a release of the pressure. An early pressure cooker, called a steam digester, was invented by Denis Papin, a French physicist, in 1679. A pressure cooker is often used by mountain climbers to compensate for the low atmospheric pressure at a very high altitude. Without it, water boils off before reaching 100 °C, leaving the food improperly cooked, as described in Charles Darwin's Voyage of the Beagle:

At the place where we slept water necessarily boiled, from the diminished pressure of the atmosphere, at a lower temperature than it does in a less lofty country; the case being the converse of that of a Papin's digester. Hence the potatoes, after remaining for some hours in the boiling water, were nearly as hard as ever. The pot was left on the fire all night, and next morning it was boiled again, but yet the potatoes were not cooked. I found out this, by overhearing my two companions discussing the cause, they had come to the simple conclusion, "that the cursed pot [which was a new one] did not choose to boil potatoes."

A larger scale version of a pressure cooker, used by laboratories and hospitals to sterilise biological waste materials, surgical instruments etc. is known as an autoclave. Category:Cooking techniques ja:圧力鍋

Simmering

Simmering is a cooking technique in which foods are cooked in hot liquids kept at or just barely below the boiling point of water (at average sea level air pressure), 100 °C (212 °F). To keep a pot simmering, one brings it to a boil and then adjusts the heat downward until just before the formation of steam bubbles stops completely. Water normally begins to simmer at about 94 °C or 200 °F. Professional chefs debate the appropriate temperature and appearance of simmering liquids constantly, with some saying that a simmer is as low as 180°F. If you are in culinary school or a professional kitchen, you should always use the chef's definition of simmering. Simmering ensures gentler treatment than boiling to prevent toughening and prevent food from breaking up. Simmering is usually a rapid and efficient method of cooking. In Japanese cuisine, simmering is considered one of the four essential cooking techniques (along with grilling, steaming, and deep frying). ---- Simmering is also the name of a district of Vienna. Category:Cooking techniques

Steaming

:For the movie, see Steaming (movie). Steaming is cooking by steam. Steaming is a preferred cooking method of health conscious individuals because no cooking oil is needed, resulting in a lower fat content. Steaming also results in a more nutritious food than boiling because fewer nutrients are destroyed or leached away into the water. Also, it does not burn the food like oil do. Steaming works by first boiling the water so it will evaporate into steam, then the steam will carry heat to the food, thus achieving heating the food. In western cooking, steaming is usually used to cook vegetables, and only rarely to cook meats. On the contrary, vegetables are seldom steamed in Chinese cuisine, vegetables are mostly stir fried or blanched instead. In Chinese cooking, steaming is used to cook many meat dishes, for example, steamed whole fish, steamed pork spare ribs, steamed ground pork or beef patties, steamed chicken, steamed goose etc. Other than meat dishes, many Chinese rice and wheat foods are steamed too. Examples include buns, Chinese steamed cakes etc. Steamed meat dishes (except some dim sum) are less common in Chinese restaurant than in traditional home cooking because meats usually require longer cooking time to steam than stir frying. blanched The Chinese chefs developed an efficient method of restaurant cooking. Big bamboo steaming baskets each three feet in diameter, four inches tall can be stacked up on top of a wok like a chimney. The bottom of each basket is a grid which allows the steam from the wok to rise all the way to the top of the stack. In kitchen of some dim sum restaurants, a steaming stack can be 20 levels high. The bottom level is removed when done and the entire stack simply shift downward. This technique ensures a constant supply of freshly steamed dim sum. Steaming at home can be done with a wok. A shelf is put on the bottom of the wok. A small steam basket or a dish of food is put on the shelf. Water is filled to just below the dish or basket. Keep the water boiling with a lid on. Most vegetable dishes are done in approximately five minutes. Most meat dishes take longer than 20 minutes. A common alternative is to put the dish on top of the rice being cooked. A pot of rice takes about 30 minutes to cook. The dish is ready when the rice is. Specialized steamers are available in the market. Although they are more convenient, they are not necessarily better. A related technique is enclosing food in a container or material that will release steam when heated, such as clay pot cooking. A kind of steaming can be done outdoors by wrapping meat, poultry, or fish in banana leaves and burying it in hot sand or ash. Another form of outdoor steam cooking is covering a large piece of meat, poultry or fish in wet clay and placing it in a fire. :See also : Cooking Category:Cooking techniques

Vacuum flask cooking

Vacuum flask cooking is an invention introduced to the Asian market in the mid 1990s. The vacuum cooker (燜燒鍋) is a stainless steel vacuum flask. The flasks come in various sizes ranging from 20-40 cm (8-16 in) in diameter, and 25 cm (10 in) tall. A removable pot, with handle and lid, is inside the vacuum flask. Food is cooked in the pot on a regular stove at a high heat. After the food is fully cooked, the pot's lid is put on and the pot is inserted into the vacuum flask. The heavily insulated lid of the flask is closed and locked air-tight. The pot and food are left in the vacuum flask for several hours. The food continues cooking in its own heat, and stays warm. The typical user prepares a meal in the morning, heats the meal in the pot, places the pot in the vacuum cooker and returns home after work to enjoy a hot meal. Normally, reheating is not required as the food remains hot enough for consumption after 6 to 8 hours. The main advantages are carefree operation, and zero power consumption during the prolonged cooking process. Note however that a reduction in power consumption is due entirely to possibly greater efficiency (ie, reduced loss of heat to the environment during cooking), as the same amount of heat energy is required to chemically transform uncooked food into cooked food in either case. The main difference is whether the heat escapes or goes into the chemical transformation of the food. Even given the same amount of heat energy, in the insulated environment, the prolonged chemical reaction more than cooks the food but instead breaks down the food so much to alter the texture of the dish. In order to achieve the same texture of the food, a regular stove might need to be burning for 6 hours or more. With the vacuum flask, the food is cooked on the stove for 20 minutes and then kept hot for 6 hours. The energy saving can be 10 to 20 fold. The main disadvantage is the risk of food poisoning as the food temperature slowly decreases to levels which may allow bacteria growth in the food. The danger of food poisoning can be reduced, but not eliminated, by thoroughly cooking the food at high temperatures before putting it in the vacuum flask. Also, it is important to buy a vacuum cooker that seals and insulates effectively, so the food temperature will be less likely to drop below a level sufficient to kill micro organisms. Vacuum flasks appeal to Cantonese cooks because many Cantonese dishes require prolonged braising or simmering. When these cookers were first introduced in the US, they sold very quickly in the larger Asian supermarkets. The vacuum flask approach is reminiscent of the familiar crock pot, in that food cooks unattended for extended periods. The differences are significant enough that neither is quite a replacement for the other. Haybox cooking is an earlier form of retained heat cooking. Note that the food is NOT cooked in a vacuum. It is cooked inside a vacuum flask. The vacuum in the wall of the cooker insulates the pot, so the food in the pot remains hot over several hours.
Note that a different kind of vacuum cooker is used in the candy manufacturing industry to cook candies at low air pressures. That is a different topic altogether.

External link

[http://www.artekusa.com/lunch/details/lunch4500.html An example of a vacuum cooker] Category:Cooking techniques

Steeping

Steeping may mean: #Soaking in liquid until saturated with a soluble ingredient. #Soaking to remove an ingredient; Example -- salt from smoked ham or salted cod. One example is the steeping of corn, part of the milling process. As described by the US Corn Refiners Association, harvested kernels of corn are cleaned and then steeped in water at a temperature of 50 degrees for 30 to 40 hours. In the process their moisture content rises from 15% to 45% and their volume more than doubles. The gluten bonds in the corn are weakened and starch is released. The corn is then ground to break free the germ and other components, and the water used (steepwater), which has absorbed various nutrients, is recycled for use in animal feeds.

References

Category:Cooking techniques

Stewing

In cooking, stewing means preparing meat cut into smaller pieces or cubes by simmering it in liquid, usually together with vegetables. A stew may be either simmered in a pot on the stove top or cooked in a covered casserole in the oven. Stewing is suitable for the least tender cuts of meat that become tender and juicy with the slow moist heat method. Cuts having a certain amount of marbling and gelatinous connective tissue give moist, juicy stews, while lean meat may easily become dry (see cooking). White stews, also known as blanquettes or fricassées, are made with lamb or veal that is blanched, or lightly seared without browning, and cooked in stock. Brown stews are made with pieces of red meat that are first seared or browned, before a browned mirepoix, sometimes browned flour, stock and wine are added. Stews may be thickened by reduction, but are more often thickened with flour, either by coating pieces of meat with flour before searing, or by using a roux or beurre manié, a dough consisting of equal parts of butter and flour. Category:Cooking techniques

Frying

Frying is the cooking of food in fat. Fats can reach higher temperatures than water at atmospheric pressure. Through frying, one can sear (or even carbonizing) the surface of foods while caramelizing sugars. Frying techniques vary in the amount of fat required, the cooking time, the type of cooking vessels required, and the techniques employed in the manipulation of the food. Sautéing, stir frying, pan frying, shallow frying, and deep frying are all standard frying techniques. Sautéing and stir-frying involve cooking foods in a thin layer of fat on a hot surface, such as a frying pan, griddle, wok, or sauteuse. Since stir fry involves quickly frying at very high temperatures, one stirs foods frequently to prevent them from adhering to the cooking surface and overcooking. Shallow frying is a type of pan frying that requires enough fat to immerse approximately one-third to two-thirds of each piece of food; deep-frying involves either the total or near-total immersion of food in hot, bubbling oil.

Hot salt frying

Hot salt frying is a technique used by street side food vendors in China. Coarse sea salt is placed in a large wok and heated to high temperature. Dry food items, such as eggs in shell, are buried in the hot salt and occasionally turned with a spatula. This technique was also observed in San Blas, Nayarit, Mexico, along the zocalo, in July of 1991. A vendor had placed a large clay cazuela on top of a 4-legged, waist high charcoal brazier. The cazuela was filled with coarse salt. After the salt became hot, the vendor toasted/fried pepitas, or pumpkin seeds in their shells in the hot salt, stirring them with a slotted spoon. When the seeds were "done", the vendor spooned them into tiny paper bags and sold them to strollers in the zocalo for an afternoon or evening snack. This technique is also seen in India where street vendors sell shelled peanuts or popcorn cooked in salt heated in an iron wok. :See also : Chinese cuisine, Cooking, Hot sand frying Category:Cooking techniques

Hot sand frying

Hot sand frying is a common technique for street side food vendors in China to cook chestnuts and peanuts. A large wok is filled with black sand and heated to high temperature. Nuts are buried in the hot sand and occasionally turned with a spatula, then the sand and nuts are separated through a wire-mesh screen.

Pressure frying

In pressure frying, meat and cooking oil are brought to high temperatures while pressure is held high enough that the water within is prevented from boiling off. This leaves the meat very hot and juicy. It is a variation on pressure cooking and is mostly done in industrial kitchens. This should be only attempted with specialized equipment made for pressure frying. It is not safe in a household pressure cooker. Category:Cooking techniques

Sautéing

Sautéing is a method of cooking food using a small amount of fat in a shallow pan over relatively high heat. Sauter means "to jump," in French, and the food being sautéed is kept moving, not unlike the stir fry technique using a wok. Food that is sautéed is usually cooked for a relative short period of time over high heat in order to preserve its color, moisture and flavor. This is very common with more tender cuts of meat, e.g. tenderloin and filet mignon. Sautéeing differs from searing in that the sautéed food is thoroughly cooked in the process. One may sear simply to seal the outside of a food before another process is used to finish cooking it. Olive oil or clarified butter are commonly used for sautéeing, but most fats will do. Regular butter is less well suited for sautéeing because it will burn at a lower temperature due to the presence of milk solids. It is important to ensure that the pan is very hot and that the food is not crowded into the pan. This ensures that the food browns well without absorbing the fat or stewing in its own juices. Furthermore, the food must be completely dry in order to keep the pan from cooling and to keep the moisture from building up in the pan; moisture will steam or stew the food. This is particularly important in the case of food that has been marinated. To sauté, use a hot pan, large enough to hold all of the food in one layer. Do not use too much fat, which will cause the food to fry rather than to sauté. Do not toss or stir the items in the pan by shaking the pan around, which causes the pan to cool faster. Let one side of the sautéed item become golden brown before tossing, turning, or flipping the item over, in order to allow the food to yield more flavor.

Microwaving

A microwave oven is a kitchen appliance employing microwave radiation primarily to cook or heat food.

History

Cooking food with microwaves was discovered by Percy Spencer while building magnetrons for radar sets at Raytheon. He was working on an active radar set when he noticed a strange sensation, and saw that a chocolate bar he had in his pocket had melted. As the holder of 120 patents, Spencer was no stranger to discovery and experiment, and realized what was happening. The first food to be deliberately cooked with microwaves was popcorn, and the second was an egg (which exploded in the face of one of the experimenters). In 1946 Raytheon patented the microwave cooking process and in 1947, the company built the first microwave oven, the Radarange. It was almost 6 feet (1.8 m) tall and weighed 750 pounds (340 kg). It was water-cooled and produced 3000 watts, about three times the amount of radiation produced by microwave ovens today. An early commercial model introduced in 1954 generated 1600 watts and sold in the $2–3000 range. Raytheon licensed its technology to the Tappan Stove company in 1952. They tried to market a large, 220 volt, wall unit as a home microwave oven in 1955 for a price of $1295, but it did not sell well. In 1965 Raytheon acquired Amana, which introduced the first popular home model, the countertop Radarange in 1967 at a price point of $495. In the 1960s, Litton bought Studebaker's Franklin Manufacturing assets, which had been manufacturing magnetrons, building, and selling microwave ovens similar to the Radarange. Litton then developed a new configuration of the microwave, the short, wide shape that is now common. The magnetron feed was also unique. This resulted in an oven that could survive a no-load condition indefinitely. The new oven was shown at a trade show in Chicago, and helped begin a rapid growth of the market for home microwave ovens. Sales figures of 40,000 units for the US industry in 1970 grew to one million by 1975. Market penetration in Japan, which had learned to build less expensive units by re-engineering a cheaper magnetron, was more rapid. A number of other companies joined in the market, and for a time most systems were built by defense contractors, who were the most familiar with the magnetron. Litton was particularly well known in the restaurant business. By the late 1970s the technology had improved to the point where prices were falling rapidly. Formerly found only in large industrial applications, "microwaves" were increasingly becoming a standard fixture of most (western) kitchens. The rapidly falling price of microprocessors also helped by adding electronic controls to make the ovens easier to use. By the late 1980s they were almost universal and currently it is estimated that nearly 95% of American households have a microwave.

Description

A microwave oven consists of:
- a magnetron,
- a magnetron control circuit (usually with a microcontroller),
- a waveguide, and
- a cooking chamber A microwave oven works by passing microwave radiation, usually at a frequency of 2450 MHz (a wavelength of 12.24 cm), through the food. Water, fat, and sugar molecules in the food absorb energy from the microwave beam in a process called dielectric heating. Most molecules are electric dipoles, meaning that they have a positive charge at one end and a negative charge at the other, and therefore vibrate as they try to align themselves with the alternating electric field induced by the microwave beam. This molecular movement creates heat. Microwave heating is most efficient on liquid water, and much less so on fats, sugars, and frozen water. Microwave heating is sometimes incorrectly explained as resonance of water molecules, which only occurs at much higher frequencies, in the tens of gigahertz. The cooking chamber itself is a Faraday cage enclosure to prevent the microwaves escaping into the surroundings. The oven door is usually a glass panel for easy viewing, but has a layer of conductive mesh to maintain the shielding. Since the mesh width is much less than the wavelength of 12 cm, the microwave radiation can not pass through the door, while visible light (with a much shorter wavelength) can. Professional chefs generally find microwave ovens to be of limited usefulness. On the other hand, people who are lacking in free time, or not comfortable with their cooking skills, can use microwave ovens to reheat stored food (including commercially available pre-cooked frozen dishes) in only a few minutes. With wireless computer networks gaining in popularity, microwave interference has become a concern near wireless networks. Microwave ovens are capable of disrupting wireless network transmissions because the oven generates radio waves of about 2450 MHz, near the 802.11b/g frequency band.

Efficiency

A microwave oven does not convert all electrical energy into microwaves. A typical consumer microwave oven could consume 1100 W, and deliver 700 W of microwave power. The remaining 400 W are dissipated as heat by components of the oven. The main source of energy loss is the magnetron tube which is much less than 100% efficient at generating microwave output from the power source. Lesser amounts of power are consumed by the oven lamp, AC power transformer losses, magnetron cooling fan, food turntable motor and control circuits. This waste heat does not end up in the food but is mostly expelled from the cooling vents on the oven and heats the air in the kitchen. See Electrical efficiency. Most of the microwave power will end up heating the food inside the oven, unless the microwave oven is loaded with a very small amount of absorbing food. In that case, the magnetron element will reabsorb the microwaves, which can lead to overheating and a fire risk.

Safety and controversy

Microwaving food is fast and popular, but there are potential hazards.

Uneven heating

Food is heated for so short a time that it is often cooked unevenly. Microwave ovens are frequently used for reheating previously cooked food, and bacterial contamination may not be killed by the reheating, resulting in foodborne illness. The uneven heating is partly due to the uneven distribution of microwave energy inside the oven, and partly due to the different rates of energy absorption in different parts of the food. The first problem is reduced by a stirrer, a type of fan that reflects microwave energy to different parts of the oven as it rotates, and by a turntable that turns the food. The second problem must be addressed by the cook, who should arrange the food so that it absorbs energy evenly, and periodically test and shield any parts of the food that overheat. In some materials with low thermal conductivity, where dielectric constant increases with temperature, microwave heating can cause localized thermal runaway.

Acute dangers

thermal runaway Liquids, when heated in a microwave oven in a container with a smooth surface, can superheat; that is, reach temperatures that are a few degrees Celsius above their normal boiling point without actually boiling. The boiling process can start explosively when the liquid is disturbed, such as when the operator grabs hold of the container to take it out of the oven, which can result in severe burns. A common myth states that only distilled water can exhibit this behavior; this is not true. [http://www.amasci.com/weird/microexp.html#myth] Closed containers and eggs can explode when heated in a microwave oven due to the pressure build-up of steam. Products that are heated too long can catch fire. Manuals of microwave ovens warn of such hazards. steam Tin foil, aluminium foil, ceramics decorated with metal, and products containing other metals can cause sparks when they are used in a microwave. Microwaving small, smooth, solid metal objects without pointed ends (for example, a spoon) can sometimes be safe, and usually does not produce sparking. Forks, however, will readily produce sparks when placed in the microwave. This is because while it acts as an antenna, absorbing microwave radiation just like other metal objects such as the spoon, the pointed ends of the fork will act to concentrate the electric field formed at the tips. This has the effect of exceeding the dielectric breakdown gradient of air, about 3 megavolts per meter (3×10⁶V/m), causing sparks to form. This effect is directly analogous to the effect of St. Elmo's fire. The formation of sparks on sharp metal objects may be prevented by placing the utensil in some food or liquid while in the microwave, as this has the effect of preferentially conductively dissipating the charge before the electric fields can build to the point where they exceed the breakdown value of air. Any time dielectric breakdown occurs in air, some ozone and nitrogen oxides are formed, both of which are toxic. Finally, as mentioned previously, any metal or conductive object placed into the microwave will act as an antenna, and its electrons will thus be thrashed back and forth through the object (a high frequency alternating current) causing some ohmic heating to occur. The extent of this heating effect will vary depending on the size, shape and conductivity of the object. Several microwave fires have been noted where chinese takeout boxes with a metal handle are microwaved, and also where "homemade" microwave popcorn bags have been sealed using a metal staple, which is then heated and sets fire to the bag. This type of accident can pose a dangerous situation because of the extremely flamable mixture of popcorn and oil in the bag. Thus, it is good practice to remove any metal utensils or metal containing objects from a microwave oven before operating it, as the behavior of these objects when immersed in a strong microwave radiation field is unpredictable. It is a common myth that metallic kitchen equipment, like kitchen forks and knives, can somehow repel the microwaves back into the magnetron and cause it to catch fire. This is highly unlikely.

Controversial hazards

Radiation

Some people are concerned with being exposed to the microwave radiation. The USA legal limit of leaking radiation is 1 mW/cm² at 5 cm from a new oven (for a used oven, it is 5 times higher). It is rare for an oven to exceed these limits. As a comparison, a GSM cellular phone may emit up to 1 W at 1800 MHz, which is 2 mW/cm² at 5 cm. Whether or not cellular phones are hazardous to the health is also controversial. The radiation produced by a microwave oven is non-ionizing. As such, it does not have the same cancer risks associated with ionizing radiation such as X-rays and ultraviolet.

Food

ultraviolet Some people claim that there exist more subtle dangers than the ones listed above associated with cooking in a microwave oven. Namely, it is often claimed that microwave cooking causes more loss of nutrients than conventional cooking and that microwave radiation leads to chemical reactions in the food that are different from those occurring during conventional heating and which can cause cancer or other ill effects if consumed. There is no accepted scientific validity to these claims, and most scientists and skeptics consider these claims to be alarmist and pseudoscientific. Examples of anti-microwave websites:
- [http://www.relfe.com/microwave.html Microwave Cooking is Killing You!]
- [http://www.mercola.com/2003/nov/5/microwave_food.htm Do You Microwave Your Food?]

External links and references

- -- Method of treating foodstuff
- [http://hps.org/hpspublications/articles/microwaveoven.html Health physics society: microwave oven safety]
- [http://www.inventionandtechnology.com/xml/2005/4/it_2005_4_feat_4.xml Microwave oven history] from American Heritage magazine
- [http://www.colorado.edu/physics/2000/microwaves How microwaves and microwave ovens work] Java animation suitable for young people.
- [http://www.gallawa.com/microtech/how_work.html How a microwave oven works] Description with circuit diagrams.
- [http://everist.org/special/mw_oven/ "Fun Things to Do with Microwave Ovens"] Includes warnings and repair tips.
- [http://web.njit.edu/~jcl7/microwave_cookbook.html "Microwave Cookbook"] Great ideas of what to cook in a microwave. Category:Electro mechanical engineering Category:Cooking appliances Category:Microwave technology ja:電子レンジ th:เตาอบไมโครเวฟ

Barbecuing

in May World Championship Barbecue Cooking Contest.]] ]] Pans on the top shelf hold hamburgers and hot dogs that were grilled earlier when the coals were hot. The lower grill is now being used to slowly cook pork ribs and "drunken chicken"]] Barbecue, (also spelled barbeque, or abbreviated BBQ) is a method of cooking meat with the heat and hot gasses of a fire, the application of a vinegar-based sauce to meat, the end-result of cooking by this method, or a party that includes such food. Barbecue is usually cooked in an outdoor environment heated by the smoke of wood, or charcoal. Restaurant barbecue may be cooked in large brick or metal ovens specially designed for that purpose. Barbecue has numerous regional variations in many parts of the world. Notably, in the South and Midwest of the U.S., practitioners consider barbecue to include only relatively indirect methods of cooking, with the more direct high-heat methods to be called grilling. For those that distinguish the terms, grilling is almost always a fast process over high heat and barbecue is almost always a slow process using indirect heat and/or hot smoke. For example, in a typical home grill, grilled foods are cooked on a grate directly over hot charcoal; while in barbecuing, the coals are dispersed to the sides or at significant distance from the grate. Alternately, an apparatus called a smoker with a separate fire box may be used. Hot smoke is drawn past the meat by convection for very slow cooking. This is essentially how barbecue is cooked in most genuine "barbecue" restaurants, but nevertheless many consider this to be a distinct cooking process called smoking. Regardless of the method, the meat should be turned several times to ensure