Misplaced Pages

#790209

68-457: Simmering ensures gentler treatment than boiling to prevent food from toughening and/or breaking up. Simmering is usually a rapid and efficient method of cooking. Food that has simmered in milk or cream instead of water is sometimes referred to as creamed . The appropriate simmering temperature is a topic of debate among chefs , with some contending that a simmer is as low as 82 °C or 180 °F. Some modern gas ranges are equipped with

136-559: A Thermosiphon or a heat pipe. Flows in flow boiling are often characterised by a void fraction parameter, which indicates the fraction of the volume in the system that is vapor. One can use this fraction and the densities to calculate the vapor quality , which refers to the mass fraction that is in the gas phase. Flow boiling can be very complex, with heavy influences of density, flow rates, and heat flux, as well as surface tension. The same system may have regions that are liquid, gas, and two-phase flow. Such two phase regimes can lead to some of

204-428: A communal fire , and can be enjoyed by all members of the family, although in many cultures women bear primary responsibility. 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

272-588: A deep cave) of controlled use of fire to cook food by archaic humans was dated to ~780,000 years ago . Anthropologists think that widespread cooking fires began about 250,000 years ago when hearths first appeared. Recently, the earliest hearths have been reported to be at least 790,000 years old. Communication between the Old World and the New World in the Columbian Exchange influenced

340-503: A desirable texture. Fats are one of the three main macronutrient groups in human diet , along with carbohydrates and proteins , and the main components of common food products like milk , butter , tallow , lard , salt pork , and cooking oils . They are a major and dense source of food energy for many animals and play important structural and metabolic functions, in most living beings, including energy storage, waterproofing, and thermal insulation . The human body can produce

408-400: A heated liquid is a complex physical process which often involves cavitation and acoustic effects, such as the broad-spectrum hiss one hears in a kettle not yet heated to the point where bubbles boil to the surface. If a surface heating the liquid is significantly hotter than the liquid then film boiling will occur, where a thin layer of vapour, which has low thermal conductivity , insulates

476-450: A heated liquid may show boiling delay and the temperature may go somewhat above the boiling point without boiling. Homogeneous nucleation, where the bubbles form from the surrounding liquid instead of on a surface, can occur if the liquid is warmer in its center, and cooler at the surfaces of the container. This can be done, for instance, in a microwave oven, which heats the water and not the container. Critical heat flux (CHF) describes

544-510: A large cranial capacity meant that early Homo habilis regularly cooked food. However, unequivocal evidence in the archaeological record for the controlled use of fire begins at 400,000 BCE, long after Homo erectus . Archaeological evidence from 300,000 years ago, in the form of ancient hearths, earth ovens , burnt animal bones, and flint , are found across Europe and the Middle East. The oldest evidence (via heated fish teeth from

612-533: A lower CHF than pool boiling. CHF occurs when the vapor momentum force at the two-phase interface balances the combined surface tension and hydrostatic forces, leading to irreversible growth of the dry spot. Confined boiling is particularly promising for electronics cooling. The boiling point of an element at a given pressure is a characteristic attribute of the element. This is also true for many simple compounds including water and simple alcohols . Once boiling has started and provided that boiling remains stable and

680-472: A method of disinfecting water, bringing it to its boiling point at 100 °C (212 °F), is the oldest and most effective way since it does not affect the taste, it is effective despite contaminants or particles present in it, and is a single step process which eliminates most microbes responsible for causing intestine related diseases. The boiling point of water is 100 °C (212 °F) at sea level and at normal barometric pressure. In places having

748-473: A minute; at boiling point, Vibrio cholerae ( cholera ) takes ten seconds and hepatitis A virus (causes the symptom of jaundice ), one minute. Boiling does not ensure the elimination of all micro-organisms; the bacterial spores Clostridium can survive at 100 °C (212 °F) but are not water-borne or intestine affecting. Thus for human health, complete sterilization of water is not required. The traditional advice of boiling water for ten minutes

SECTION 10

#1732786913791

816-424: 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 via Maillard reaction . These compounds impart colors, tastes and smells that are specific to these food, but may also be deleterious to health. Dry heat (e.g. in roasting or grilling) can significantly increase

884-519: A number of ways in cooking and baking. To prepare stir fries , grilled cheese or pancakes , the pan or griddle is often coated with fat or oil. Fats are also used as an ingredient in baked goods such as cookies , 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

952-724: A per calorie basis while providing more fiber , calcium , and iron . 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 preventing chronic disease . 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. "Home-cooking" may be associated with comfort food , and some commercially produced foods and restaurant meals are presented through advertising or packaging as having been "home-cooked", regardless of their actual origin. This trend began in

1020-650: A proper water purification system, it is recommended only as an emergency treatment method or for obtaining potable water in the wilderness or in rural areas, as it cannot remove chemical toxins or impurities. The elimination of micro-organisms by boiling follows first-order kinetics —at high temperatures, it is achieved in less time and at lower temperatures, in more time. The heat sensitivity of micro-organisms varies, at 70 °C (158 °F), Giardia species (which cause giardiasis ) can take ten minutes for complete inactivation, most intestine affecting microbes and E. coli ( gastroenteritis ) take less than

1088-405: A simmering burner, with such burners usually located at the rear of the range. Many electric ranges have a simmer setting. Slow cookers are countertop electrical appliances used to simmer foods for hours at a time. In Japanese cuisine , simmering is often considered one of the four essential cooking techniques, along with grilling, steaming, and deep frying. Food prepared in a crockpot

1156-399: A subdiscipline of food science concerning the physical and chemical transformations that occur during cooking. Important contributions have been made by scientists, chefs and authors such as Hervé This (chemist), Nicholas Kurti (physicist), Peter Barham (physicist), Harold McGee (author), Shirley Corriher (biochemist, author), Robert Wolke (chemist, author.) It is different for

1224-483: A toasted crust is formed generates significant concentrations of acrylamide . 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". Cooking food at high temperature may create advanced glycation end-products (AGEs) that are believed to be involved in

1292-470: A wide variety of foods, and processed cereals quickly became a defining feature of the American breakfast. In the 1920s, freezing methods , cafeterias , and fast food restaurants emerged. Most ingredients in cooking are derived from living organisms . Vegetables, fruits, grains and nuts as well as herbs and spices come from plants, while meat, eggs, and dairy products come from animals. Mushrooms and

1360-403: Is best known as a means of separating ethanol from water. Most types of refrigeration and some type of air-conditioning work by compressing a gas so that it becomes liquid and then allowing it to boil. This adsorbs heat from the surroundings cooling the fridge or freezer or cooling the air entering a building. Typical liquids include propane , ammonia , carbon dioxide or nitrogen . As

1428-641: Is especially prone to oxidation during cooking and may be completely destroyed by protracted cooking. The bioavailability of some vitamins such as thiamin , vitamin B6 , niacin , folate , and carotenoids are increased with cooking by being freed from the food microstructure. Blanching or steaming vegetables is a way of minimizing vitamin and mineral loss in cooking. 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

SECTION 20

#1732786913791

1496-408: Is held at 100 °C (212 °F) for one minute, most micro-organisms and viruses are inactivated. Ten minutes at a temperature of 70 °C (158 °F) is also sufficient to inactivate most bacteria. Boiling water is also used in several cooking methods including boiling, steaming , and poaching . The lowest heat flux seen in boiling is only sufficient to cause [natural convection], where

1564-418: Is mainly for additional safety, since microbes start getting eliminated at temperatures greater than 60 °C (140 °F) and bringing it to its boiling point is also a useful indication that can be seen without the help of a thermometer , and by this time, the water is disinfected. Though the boiling point decreases with increasing altitude, it is not enough to affect the disinfecting process. Boiling

1632-722: 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: As of 2021, over 2.6 billion people cook using open fires or inefficient stoves using kerosene , biomass , and coal as fuel. 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 from pneumonia , 27% from ischaemic heart disease , 20% from chronic obstructive pulmonary disease , 18% from stroke , and 8% from lung cancer . Women and young children are disproportionately affected, since they spend

1700-469: Is no high-quality evidence for its efficacy against human diseases. The United States Department of Agriculture has studied retention data for 16 vitamins, 8 minerals, and alcohol for approximately 290 foods across various cooking methods. In a human epidemiological analysis by Richard Doll and Richard Peto in 1981, diet was estimated to cause a large percentage of cancers. Studies suggest that around 32% of cancer deaths may be avoidable by changes to

1768-427: Is simmered. Examples include stews , chili , soups , etc. Bulgarian traditional food, especially tender meat dishes are often simmered for extended periods of time. Examples include stews , soups , Vanyas, etc. In traditional Dutch and Flemish cuisine, less tender cuts of beef are simmered for several hours to obtain carbonade flamande . Traditionally a small flame is used, fed by burning oil. On modern stoves,

1836-415: Is the method of cooking food in boiling water or other water-based liquids such as stock or milk . Simmering is gentle boiling, while in poaching the cooking liquid moves but scarcely bubbles. The boiling point of water is typically considered to be 100 °C (212 °F; 373 K), especially at sea level. Pressure and a change in the composition of the liquid may alter the boiling point of

1904-522: Is the rapid phase transition from liquid to gas or vapour ; the reverse of boiling is condensation . Boiling occurs when a liquid is heated to its boiling point , so that the vapour pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding atmosphere. Boiling and evaporation are the two main forms of liquid vapourization . There are two main types of boiling: nucleate boiling where small bubbles of vapour form at discrete points, and critical heat flux boiling where

1972-421: Is uncooked or done rare , and unboiled water. The sterilizing effect of cooking depends on temperature, cooking time, and technique used. Some food spoilage bacteria such as Clostridium botulinum or Bacillus cereus can form spores that survive cooking or boiling, which then germinate and regrow after the food has cooled. This makes it unsafe to reheat cooked food more than once. Cooking increases

2040-640: The National 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. 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

2108-432: The culinary arts , is the art, science and craft of using heat to make food more palatable , digestible , nutritious , or safe . Cooking techniques and ingredients vary widely, from grilling food over an open fire , to using electric stoves , to baking in various types of ovens , reflecting local conditions. Cooking is an aspect of all human societies and a cultural universal . Types of cooking also depend on

Simmering - Misplaced Pages Continue

2176-406: The specific 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 and density that determines how long it will take for the food to reach a certain temperature. Home cooking has traditionally been a process carried out informally in a home or around

2244-543: The " Danger zone " temperature range from 40 to 140 °F (4 to 60 °C), food therefore 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, are good practices in food preparation. Foods prepared on plastic cutting boards may be less likely to harbor bacteria than wooden ones. Washing and disinfecting cutting boards, especially after use with raw meat, poultry, or seafood, reduces

2312-710: The Atlantic from the Old World, such as cattle , sheep , pigs , wheat , oats , barley , rice , apples , pears , peas , chickpeas , mustard , and carrots , similarly changed New World cooking. In the 17th and 18th centuries, food was a classic marker of identity in Europe. In the 19th-century "Age of Nationalism ", cuisine became a defining symbol of national identity. The Industrial Revolution brought mass-production, mass-marketing, and standardization of food. Factories processed, preserved, canned, and packaged

2380-558: 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). 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 named Maillard reactions . Cooking foods with heat depends on many factors:

2448-485: The best heat transfer coefficients of any system. Confined boiling refers to boiling in confined geometries, typically characterized by a Bond number that compares the gap spacing to the capillary length. Confined boiling regimes begin to play a major role when Bo < 0.5. This boiling regime is dominated by "vapour stem bubbles" left behind after vapour departs. These bubbles act as seeds for vapor growth. Confined boiling typically has higher heat transfer coefficient but

2516-527: The boiling surface is heated above a certain critical temperature and a film of vapour forms on the surface. Transition boiling is an intermediate, unstable form of boiling with elements of both types. The boiling point of water is 100 °C or 212 °F but is lower with the decreased atmospheric pressure found at higher altitudes. Boiling water is used as a method of making it potable by killing microbes and viruses that may be present. The sensitivity of different micro-organisms to heat varies, but if water

2584-480: The case of potatoes where most vitamin C is in the skin. However, research has shown that in the specific case of carotenoids a greater proportion is absorbed from cooked vegetables than from raw vegetables. Sulforaphane , a glucosinolate breakdown product, is present in vegetables such as broccoli , and is mostly destroyed when the vegetable is boiled. Although there has been some basic research on how sulforaphane might exert beneficial effects in vivo, there

2652-684: The case with some other Iranian dishes like Abgoosht , Bozbash , etc. Simmering is the main cooking techinque used in Shabbat stews because by Jewish law cooking is forbidden on Shabbat . Almost every Jewish diaspora group has had different versions of sabbath stews, with the common practice of boiling before Sabbath begins and than keeping the pot on a blech or other device to heat the food. Many Shabbat dishes are simmered overnight to conform to Jewish law, including cholent ( Ashkenazi Jewish ), hamin ( Sepharadi Jewish ) and t'bit ( Iraqi Jewish ). Boiling Boiling or ebullition

2720-401: The common sugar, sucrose (table sugar), a disaccharide , and such simple sugars as glucose (made by enzymatic splitting of sucrose) and fructose (from fruit), and starches from sources such as cereal flour, rice, arrowroot and potato. The interaction of heat and carbohydrate is complex. Long-chain sugars such as starch tend to break down into more digestible simpler sugars . If

2788-412: The diet. 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. Several studies published since 1990 indicate that cooking meat at high temperature creates heterocyclic amines (HCA's), which are thought to increase cancer risk in humans. Researchers at

Simmering - Misplaced Pages Continue

2856-437: The digestibility of many foods which are inedible or poisonous when raw. For example, raw cereal grains are hard to digest, while kidney beans are toxic when raw or improperly cooked due to the presence of phytohaemagglutinin , which is inactivated by cooking for at least ten minutes at 100 °C (212 °F). Food safety depends on the safe preparation, handling, and storage of food. Food spoilage bacteria proliferate in

2924-635: The dish being cooked. In European cooking, a mixture of butter and flour called a roux is used to thicken liquids to make stews or sauces. In Asian cooking, a similar effect is obtained from a mixture of rice or corn starch and water. These techniques rely on the properties of starches to create simpler mucilaginous saccharides during cooking, which causes the familiar thickening of sauces . This thickening will break down, however, under additional heat. Types of fat include vegetable oils , animal products such as butter and lard , as well as fats from grains, including maize and flax oils. Fats are used in

2992-711: The fat it requires from other food ingredients, except for a few essential fatty acids that must be included in the diet. Dietary fats are also the carriers of some flavor and aroma ingredients and vitamins that are not water-soluble . Edible animal material, including muscle , offal , milk, eggs and egg whites , contains substantial amounts of protein. Almost all vegetable matter (in particular legumes and seeds ) also includes proteins, although generally in smaller amounts. Mushrooms have high protein content. Any of these may be sources of essential amino acids . When proteins are heated they become denatured (unfolded) and change texture. In many cases, this causes

3060-460: The history of cooking. The movement of foods across the Atlantic from the New World, such as potatoes , tomatoes , maize , beans , bell pepper , chili pepper , vanilla , pumpkin , cassava , avocado , peanut , pecan , cashew , pineapple , blueberry , sunflower , chocolate , gourds , green beans , and squash , had a profound effect on Old World cooking. The movement of foods across

3128-780: The invention of pottery for holding and boiling of water , expanded cooking techniques. Some modern cooks apply advanced scientific techniques to food preparation to further enhance the flavor of the dish served. Phylogenetic analysis suggests that early hominids may have adopted cooking 1 million to 2 million years ago. Re-analysis of burnt bone fragments and plant ashes from the Wonderwerk Cave in South Africa has provided evidence supporting control of fire by early humans by 1 million years ago. In his seminal work Catching Fire: How Cooking Made Us Human , Richard Wrangham suggested that evolution of bipedalism and

3196-423: The liquid. High elevation cooking generally takes longer since boiling point is a function of atmospheric pressure . At an elevation of about one mile (1,600 m), water boils at approximately 95 °C (203 °F; 368 K). Depending on the type of food and the elevation, the boiling water may not be hot enough to cook the food properly. Similarly, increasing the pressure as in a pressure cooker raises

3264-407: The molecules in a liquid have varying kinetic energies. Some high energy particles on the liquid surface may have enough energy to escape the intermolecular forces of attraction of the liquid and become a gas. This is called evaporation. Evaporation only happens on the surface while boiling happens throughout the liquid. When a liquid reaches its boiling point bubbles of gas form in it which rise into

3332-845: The most time near the hearth. Hazards while cooking can include To prevent those injuries there are protections such as cooking clothing, anti-slip shoes, fire extinguisher and more. Cooking can prevent many foodborne illnesses that would otherwise occur if raw food is consumed. When heat is used in the preparation of food, it can kill or inactivate harmful organisms, such as bacteria and viruses, as well as various parasites such as tapeworms and Toxoplasma gondii . Food poisoning and other illness from uncooked or poorly prepared food may be caused by bacteria such as pathogenic strains of Escherichia coli , Salmonella typhimurium and Campylobacter , viruses such as noroviruses , and protozoa such as Entamoeba histolytica . Bacteria, viruses and parasites may be introduced through salad, meat that

3400-492: 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 of scratch made , and factory made foods together to make a meal . The nutritional value of including more commercially prepared foods has been found to be inferior to home-made foods. Home-cooked meals tend to be healthier with fewer calories, and less saturated fat , cholesterol and sodium on

3468-423: The pressure is constant, the temperature of the boiling liquid remains constant. This attribute led to the adoption of boiling points as the definition of 100 °C. Mixtures of volatile liquids have a boiling point specific to that mixture producing vapour with a constant mix of components - the constant boiling mixture . This attribute allows mixtures of liquids to be separated or partly separated by boiling and

SECTION 50

#1732786913791

3536-399: 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. The scientific study of cooking has become known as molecular gastronomy. This is

3604-775: The remaining flavor and ingredients; this is a critical component of both stewing and sauce making. Vitamins and minerals are required for normal metabolism ; 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 and sulfur ; and in very small quantities copper, zinc and selenium . The micronutrients, minerals, and vitamins in fruit and vegetables may be destroyed or eluted by cooking. Vitamin C

3672-405: The risk of contamination. Proponents of raw 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 containing vitamin 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

3740-608: The skill levels and training of the cooks . Cooking is done both by people in their own dwellings and by professional cooks and chefs in restaurants and other food establishments. Preparing food with heat or fire is an activity unique to humans . 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. The expansion of agriculture , commerce , trade , and transportation between civilizations in different regions offered cooks many new ingredients. New inventions and technologies, such as

3808-454: The source of heat is put very low, or a simmering plate is used to diminish the heat. Usually a cast iron pan is used with a thick bottom. The meat is ready if it can be easily torn apart into threads. Simmering is one of the most popular styles of cooking in Iran and Afghanistan. In traditional Persian cuisine , almost all types of Persian Khoresh are simmered for several hours. That is also

3876-505: The structure of the material to become softer or more friable – meat becomes cooked and is more friable and less flexible. In some cases, proteins can form more rigid structures, such as the coagulation of albumen 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 on meringue . Cooking often involves water, and water-based liquids. These can be added in order to immerse

3944-538: 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 other recipes . 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 in steaming , simmering , boiling , braising and blanching . Heating liquid in an open container results in rapidly increased evaporation , which concentrates

4012-490: The sugars are heated so that all water of crystallisation is driven off, caramelization starts, with the sugar undergoing thermal decomposition with the formation of carbon , and other breakdown products producing caramel . Similarly, the heating of sugars and proteins causes the Maillard reaction , a basic flavor-enhancing technique. An emulsion of starch with fat or water can, when gently heated, provide thickening to

4080-459: The surface and burst into the air. This process is called boiling. If the boiling liquid is heated more strongly the temperature does not rise but the liquid boils more quickly. This distinction is exclusive to the liquid-to-gas transition; any transition directly from solid to gas is always referred to as sublimation regardless of whether it is at its boiling point or not. Cooking Cooking , also known as cookery or professionally as

4148-444: The surface, the temperature rises very rapidly beyond this point into the transition boiling regime. The point at which this occurs is dependent on the characteristics of boiling fluid and the heating surface in question. Transition boiling may be defined as the unstable boiling, which occurs at surface temperatures between the maximum attainable in nucleate and the minimum attainable in film boiling. The formation of bubbles in

SECTION 60

#1732786913791

4216-479: The surface. This condition of a vapour film insulating the surface from the liquid characterises film boiling . "Pool boiling" refers to boiling where there is no forced convective flow. Instead, the flow occurs due to density gradients. It can experience any of the regimes mentioned above. "Flow boiling" occurs when the boiling fluid circulates, typically through pipes. Its movement can be powered by pumps, such as in power plants, or by density gradients, such as in

4284-473: The temperature of the contents above the open air boiling point. Also known as "boil-in-bag", this involves heating or cooking ready-made foods sealed in a thick plastic bag. The bag containing the food, often frozen, is submerged in boiling water for a prescribed time. The resulting dishes can be prepared with greater convenience as no pots or pans are dirtied in the process. Such meals are available for camping as well as home dining. At any given temperature,

4352-453: The temperature of the liquid. In general, the number of nucleation sites is increased by an increasing surface temperature. An irregular surface of the boiling vessel (i.e., increased surface roughness) or additives to the fluid (i.e., surfactants and/or nanoparticles ) facilitate nucleate boiling over a broader temperature range, while an exceptionally smooth surface, such as plastic, lends itself to superheating . Under these conditions,

4420-435: The thermal limit of a phenomenon where a phase change occurs during heating (such as bubbles forming on a metal surface used to heat water ), which suddenly decreases the efficiency of heat transfer , thus causing localised overheating of the heating surface. As the boiling surface is heated above a critical temperature, a film of vapour forms on the surface. Since this vapour film is much less capable of carrying heat away from

4488-442: The time needed for the meat to be cooked at high heat. 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. Baking, grilling or broiling food, especially starchy foods, until

4556-420: The warmer fluid rises due to its slightly lower density. This condition occurs only when the superheat is very low, meaning that the hot surface near the fluid is nearly the same temperature as the boiling point. Nucleate boiling is characterised by the growth of bubbles or pops on a heated surface (heterogeneous nucleation), which rises from discrete points on a surface, whose temperature is only slightly above

4624-405: The yeast used in baking are kinds of fungi . Cooks also use water and minerals such as salt . Cooks can also use wine or spirits . Naturally occurring ingredients contain various amounts of molecules called proteins , carbohydrates and fats . They also contain water and minerals. Cooking involves a manipulation of the chemical properties of these molecules. Carbohydrates include

#790209