Deep frying

Deep frying(also referred to asdeep fat frying) is acookingmethod in which food is submerged in hotfat, traditionallylardbut today most commonlyoil, as opposed to theshallow fryingused in conventionalfryingdone in afrying pan. Normally, adeep fryerorchip panis used for this; industrially, apressure fryerorvacuum fryermay be used. Deep frying may also be performed using oil that is heated in a pot. Deep frying is classified as a hot-fat cooking method.Typically, deep frying foods cook quickly since oil has a high rate of heat conduction and all sides of the food are cooked simultaneously.
The term "deep frying" and many modern deep-fried foods were not invented until the 19th century, but the practice has been around for millennia. Early records and cookbooks suggest that the practice began in certain European countries before other countries adopted the practice.
Deep frying is popular worldwide, with deep-fried foods accounting for a large portion of global caloric consumption.
The English expressiondeep-friedis attested from the early 20th century.
Deep-fried dough known asZalabiyehwas eaten as early as the late 2nd millennium BCE inCanaan. Frying food inolive oilis attested inClassical Greecefrom about the 5th century BCE.The, 5th century CE, Roman cookbookApiciusoffers a recipe for deep fried chicken in a cream sauce "Pullus leucozomus".The practice of deep frying spread to other parts ofEuropeandAmericain the following centuries. Deep-fried foods such asfunnel cakesarrived in northern Europe by the 13th century,and deep-fried fish recipes have been found in cookbooks in Spain and Portugal at around the same time.Falafelarrived in theMiddle EastfromEgyptas early as the 14th century.
French fries, invented in the late 18th century, became popular in the early 19th century western Europe.In 1860, Joseph Malin combineddeep fried fish with chips(french fries) to open the first fish and chip shop in London.
Modern deep frying in the United States began in the 19th century with the growing popularity ofcast iron, particularly around theAmerican Southwhich led to the development of many modern deep-fried dishes.Doughnutswere invented in the mid-18th century,with foods such asonion rings,deep-fried turkey,andcorn dogsall being invented in the early 20th century. In recent years, the growth offast foodhas expanded the reach of deep-fried foods,especially french fries.
Deep frying food is defined as a process where food is submerged in hot oil at temperatures typically between 350 °F (177 °C) and 375 °F (191 °C), but deep frying oil can reach temperatures of over 400 °F (205 °C).One common method for preparing food for deep frying involves adding multiple layers ofbatteraround the food, such as cornmeal, flour, ortempura; breadcrumbs may also be used.
While most foods need batter coatings for protection, it is not as necessary for cooked noodles and potatoes because their high starch content enables them to hold more moisture and not shrink. Meats are sometimes cooked before deep frying to ensure that they are done inside while keeping juiciness.
When performed properly, deep frying does not make food excessively greasy, because the moisture in the food repels the oil. The hot oil heats the water within the food,steamingit; oil cannot go against the direction of this powerful flow because (due to its high temperature) the water vapor pushes the bubbles toward the surface.As long as the oil is hot enough and the food is not immersed in the oil for too long, oil penetration will be confined to the outer surface. Foods deep-fried at proper temperatures typically absorb "no more than a couple of tablespoons per2+1⁄2cups of oil" used.This oil absorption rate is around the same as occurs with shallow frying,such as in a pan.
However, if the food is cooked in the oil for too long, much of the water will be lost and the oil will begin to penetrate the food. The correct frying temperature depends on the thickness and type of food, but in most cases it lies between 350–375 °F (177–191 °C).An informal test for a temperature close to this range involves adding a tiny amount of flour into the oil and watching to see if it sizzles without immediately burning. A second test involves adding one piece of food to deep fry and watching it sink somewhat and rise back up. Sinking without resurfacing indicates that the oil is too cold; not sinking at all indicates that the oil is too hot.
It is recommended that deep fryers be cleaned often to prevent contamination.The process of cooking with oil can also contaminate nearby surfaces as oil may splatter on adjacent areas. Oil vapors can also condense on more distant surfaces such as walls and ceilings. Supplies such as dish detergent and baking soda can effectively clean affected surfaces.
Deep frying is done with adeep fryer, a pan such as awokorchip pan, aDutch oven, or a cast-iron pot. Additional tools include fry baskets, which are used to contain foods in a deep fryer and to strain foods when removed from the oil, andcooking thermometers, used to gauge oil temperature. Tongs,slotted spoons,wooden spoons, andsievesmay be used to remove or separate foods from the hot oil.
Japanese deep frying tools include long metal chopsticks; theagemono-nabedeep frying pot, which is heavy for retaining heat and deep for holding oil; theami-shakushinet ladle used for scooping out batter debris; and theabura-kirioil drying rack pan.
Deep-fried foods are common in many countries, and have also been described as "a staple of almost allstreet cuisineson all continents".There are hundreds of dishes that are associated with deep frying as most foods can be deep-fried. Examples of food that can be deep-fried include meat, poultry, fish and vegetables.Fish and chips, for instance, combines deep-fried fish and deep-friedpotatoes. French fries,doughnuts,onion rings, andhushpuppiesare common deep-fried foods.Other common deep-fried foods include Chineseyou Bingdeep-friedpancakes,Southeast Asianjin deui, and Japanese tempura. Less common deep-fried foods includemaple leaves,peanut butter and jelly sandwiches,pizza,Mars andSnickersbars.
In the United States, theChicago Tribunenotes that "you can deep fry almost anything".The American South has been noted as a modern center of innovation in the area of deep-fried food. According to the owner of a deep frying restaurant in the South, "If something is edible, you can bet that someone south of theMason-Dixon linehas tried to cook it in oil".
In Northern Africa, deep-fried dishes are a part of the cuisine.A common food in this region is the deep-friedfritter, also referred to as "sponges".In East Africa deep fried food is common, cooked in cast iron or earthenware pots.  Frying in batter is common. A Ugandan specialty is a kind of doughnut called Mandazi.  In areas of Southern Africa, street foods include deep-fried potato and cassava chips.Deep-fried foods in the country of South Africa include fish and chips,vetkoekandkoeksisters,among others.
Japanesetempurais a popular deep-fried foodthat generally consists of battered and fried seafood and vegetables. Japanese deep-fried dishes, orAgemono, include other styles besides tempura, such asKaraage,Korokke,Kushikatsu, andTonkatsu.
In areas ofSoutheast Asiasuch as Thailand,insectsare commonly deep-fried for human consumption.Western-style fast food items such as donuts, deep-fried chicken, and deep-fried potatoes are also becoming popular in Asia.
InIndonesiadeep fried food is quite common, serving as either a main dish or a snack. The ingredients are usually deep fried inpalm oil, the most widely used cooking oil in the country. Some popular deep fried foods includeayam goreng(chicken),pecel lele(catfish),pempek(fishcake) andtempeh.Fritters in Indonesia is generally identified asgorengan, the most popular one includingpisang goreng(banana fritter),bakwan jagung(corn) andtahu goreng(tofu).
Deep-fried fish,tofu, andchả giòare commonly eaten inVietnamese cuisine.Deep frying is also used to make several kinds ofbánh, includingbánh rán(fried rice ball),bánh cam(sesame ball),bánh tiêu(hollow doughnut),bánh rế(sweet potato pancake),bánh chuốichiên(banana fritter),Hồ Tây–stylebánh tôm(shrimp fritter), andbánh gối(pillow cake).
Deep-fried sticks of dough, known asyoutiaoin Chinese, are eaten in many East and Southeast Asian cuisines.
In Hong Kong,deep-fried intestine of pigsis a popular food.
InSouth Asia, popular deep fried snacks aresamosa,jalebi, andpakora.
Many countries such as theUnited Kingdomuse pure orhydrogenatedrapeseed oilfor deep-frying.Fish and chipsis a very popular deep-fried dish in England since it originated in London in the 19th century and became popular among the working class. Its popularity continues with 229 million portions of fish and chips being sold annually in England.
There is an annual trade fair devoted to deep-fried foods called the International Symposium on Deep-Fat Frying which features discussions on deep fat frying as well as exhibitions by companies involved with the process.
Belgian tradition requiresFrench friesto be deep-fried in filtered fat ofcattle, locally calledblanc de boeuforossewit.
The Mediterranean diets traditionally use olive oil for deep-frying, which it is absorbed by the food in the process. Research indicates thatvirgin olive oilis unique among other cooking oils because it is very rich in monounsaturated fatty acids and contains beneficial micronutrients.
Thedeep-fried Mars baroriginated in Scotland,with The Carron Fish Bar in Stonehaven claiming to have invented it in the early 1990s.
In the United States,soybean oilis often used for deep-frying.Beignets, originally a French dish, are a popular deep-fried pastry in the U.S. city ofNew Orleans. Deep-fried food has been a core part of the culture of the American South with many restaurants solely serving deep-fried foods. The owner of one such restaurant has said of deep-fried food that "in the South it's a way of life".Fast food is one of the most common ways to consume deep-fried food in North America.
Novelty deep-fried foods are popular today in Americanfairs, especially those in the American South.Hundreds of items are served at these fairs. Some of them include deep-fried beer, butter, and bubblegum. Additionally, deep frying can be used as a form of artwork by frying non-edible objects, such aselectronics.Artists such as Henry Hargreaves have deep-fried replicas of electronic items such asiPads,Game Boys, andlaptops.
Deep-fried food contests are frequently held at fairs such as theTexas State Fair, where they hold an annual contest for the most creative deep-fried food.Notable past winners have includedfried Cokeanddeep-fried butter, both invented byAbel Gonzales.Since 2013, an American reality competition show calleddeep-fried Masters, produced byDiscovery Networks, holds deep frying competitions at several state fairs across the country.
Fish and chipshops in Australia may purvey several types of deep-fried foods, along with other food types.
Thebuñuelo, a fried dough ball popular in Central America and Greece, is a popular deep-friedsnackand street food in South America.Picarone, a Peruvian dessert originated in the colonial period, are deep-fried doughs made with pumpkin and sweet potatoes, popular in Peru and Chile, especially during harvest festivals.,a family of deep fried cakes is well known across,sopaipillasa Chilean bread are deep fried  in oil or butter also made with pumpkin, Chancay a Peruvian bread made of flour, salt andyeast, known aschipácuerito in Paraguay andTorta fritainArgentinaandUruguay, made of flour, salt and yeast, sometimes addition with milk andanimal fatand fried in  cow fat, thechurro, a fried dough popular inSpainis a popular fried snack and street food in Argentina and Uruguay,milanesaa deep fried breadedvealbeeffrom Argentina, Paraguay and Uruguay.
Deep fat frying involves heating oil to temperatures in excess of 180 °C in the presence of moisture and air. These conditions can induce a series of complex chemical reactions which may impact the quality of both the food and the oil it is cooked in. Examples of different chemical reactions include the production offree radicals,oxidation,hydrolysis,isomerizationandpolymerization. The exact reactions are dependent upon factors such as the oil type, frying conditions, and food being cooked. When frying, water can attack the ester linkage of triacylglycerols, resulting in mono- and diglycerols, glycerol, and free fatty acids (a type ofhydrolysisreaction). The aforementioned hydrolysis reaction is enhanced by the producedfatty acidsand other low molecular weight acid compounds.
Overheating or over-using the frying oil leads to formation ofrancid-tastingproducts ofoxidation,polymerization, and other deleterious, unintended or even toxic compoundssuch asacrylamide(fromstarchyfoods).  Recent research suggests fat deterioration may be worse when fat or oil is fried with food than when fat or oil is tested on its own in a laboratory.Deep-frying under vacuumhelps to significantly reduce acrylamide formation,but this process is not widely used in thefood industrydue to the high investment cost involved.
Some useful tests and indicators of excessive oil deterioration are the following:
Instruments that indicate total polar compounds, currently the best single gauge of how deep-fried an object is, are available with sufficient accuracy for restaurant and industry use.
Cooking oil is notflammableat room temperature but can become flammable when used at high temperatures.Fires ensue if it gets ignited under these conditions.Further, attempts to extinguish an oil fire with water can cause an extremely dangerous condition (aslopover)as they cause the water to flash into steam due to the high heat of the oil, in turn sending the burning oil in all directions and thus aggravating the fire. This is the leading cause of house fires in the United Kingdom. Instead, oil fires must be extinguished with a class Ffire extinguisheror by starving the fire of oxygen, such as can be accomplished by putting a lid back on the pan or using afire blanket. Other means of extinguishing an oil fire include application of dry powder (e.g.,baking soda, salt)orfirefighting foam. Most commercial deep fryers are equipped with automaticfire suppression systemsusing foam.
Spilled hot cooking oil can also cause severethird degree burns,In the worst-case scenario, severe burns can be fatal. The higher temperaturesand tendency of oil to stick to the skin make spilled hot cooking oil far more dangerous than spilled hot water. Children can accidentally place their hands on top of the stove, play with the materials while being cooked, or accidentally pull the pot down, which can cause significant injury.If children are present, the utmost care should be used when deep frying so that their safety can be protected at all times.
Deep frying produces large amounts ofwaste oil, which must be disposed of properly. Waste oil can contribute to the creation offatbergs, overflow sewage systems, bind to the walls of sewage pipes, and interfere with sewage treatment.Waste oil from deep frying is increasingly being recycled and refined intobiodiesel.
The heating element in a deep fryer consumes enormous energy, electricity or otherwise. According to one source, an average home appliance deep fryer draws 2,000 watts.Potatoes that are stored in artificially humidified warehouses contain more water, which makes the time required to deep fry them into chips longer. This increases thecarbon dioxide footprintof commercially producing chips because more energy is required for frying over a longer time.
The process of deep frying food is generally detrimental to its nutritional value. The oils that foods absorb in their batter typically contain large amounts ofsaturated fatsandtrans fats. Consumption of large amounts of saturated and trans fats has been linked to a higher risk for somecancers.
Eating deep-fried foods has also been linked to highercholesterollevels,obesity,heart attacks, anddiabetes.Deep-fried foods cooked at certain temperatures can also containacrylamide. This discovery in 2002 led to international health concerns. Subsequent research has however found that it is not likely that theacrylamidesin burnt or well-cooked food cause cancer in humans;Cancer Research UKcategorizes the idea that burnt food causes cancer as a "myth".
Additionally, fat degradation processes (lipid peroxidation) during deep frying results in the loss of nutritional value in deep-fried foods.
Cooking oil that has been used for too long may in addition cause blood pressure elevationand vascular hypertrophy.
Trans fatsare used in shortenings for deep-frying in restaurants, as they can be used for longer than most conventional oils before becoming rancid. In the early 21st century, non-hydrogenated vegetable oils that have lifespans exceeding that of the frying shortenings became available.As fast-food chains routinely use different fats in different locations, trans fat levels in fast food can have large variations.The amount of trans fat that is formed during frying appears to increase with frying temperature, frying time, oil oxidation, and oil reuse.
Some studies have found that deep frying in olive and sunflower oils has been found to be less of a detriment to health and in some cases have positive effects oninsulinlevels.Oil can be reused a few times after original use after straining out solids.However, excessive use of the same oil can cause it to break down and release compounds into the food that may be carcinogenic, affect liver health, or influence the body's ability to absorb vitamins. Some European countries have set public health standards for the safety of frying oil.