History
The history of cooking vessels before the development of pottery is minimal due to the limited archaeological evidence. It has been possible to extrapolate likely developments based on methods used by latter peoples. Among the first of the techniques believed to be used by stone age civilizations were improvements to basic roasting. In addition to exposing food to direct heat from either an open fire or hot embers it is possible to cover the food with clay or large leaves before roasting to preserve moisture in the cooked result. Examples of similar techniques are still in use in many modern cuisines.
Of greater difficulty was finding a method to boil water. For people without access to natural heated water sources, such as hot springs, heated stones could be placed in a water-filled vessel to raise its temperature (for example, a leaf-lined pit or the stomach from animals killed by hunters). In many locations the shells of turtles or large mollusks provided a source for waterproof cooking vessels. Bamboo tubes sealed at the end with clay provided a usable container in Asia, while the inhabitants of the Tehuacan Valley began carving large stone bowls that were permanently set into a hearth as early as 7000 BC.
According to Frank Hamilton Cushing, native American cooking baskets used by the Zuni (Zuñi) developed from mesh casings woven to stabilize gourd water vessels. He reported witnessing cooking basket use by Havasupai in 1881. Roasting baskets covered with clay would be filled with wood coals and the product to be roasted. When the thus hardened clay separated from the basket, it would become a usable clay roasting pan in itself. This indicates a steady progression from use of woven gourd casings to waterproof cooking baskets to pottery. Other than in many other cultures, native Americans used and still use the heat source inside the cookware. Cooking baskets are filled with hot stones and roasting pans with wood coals. Native Americans, both in the East and in the West, would form a basket from large leaves to boil water, according to historian and novelist Louis L'Amour. As long as the flames did not reach above the level of water in the basket, the leaves would not burn through.
The development of pottery allowed for the creation of fireproof cooking vessels in a variety of shapes and sizes. Coating the earthenware with some type of plant gum, and later ceramic glazes, converted the porous container into a waterproof vessel. The earthenware cookware could then be suspended over a fire through use of a tripod or other apparatus, or even be placed directly into a low fire or coal bed as in the case of the pipkin. Ceramics (including stoneware and glass) conduct poorly, however, so ceramic pots must cook over relatively low heats and over long periods of time (most modern ceramic pots will crack if used on the stovetop, and are only intended for the oven). Even after metal pots have come into widespread use, earthenware pots are still preferred among the less well-off, globally, due to their low production cost.
The development of bronze and iron metalworking skills allowed for cookware made from metal to be manufactured, although adoption of the new cookware was slow due to the much higher cost. After the development of metal cookware there was little new development in cookware, with the standard Medieval kitchen utilizing a cauldron and a shallow earthenware pan for most cooking tasks, with a spit employed for roasting.
By the 17th century, it was common for a Western kitchen to contain a number of skillets, baking pans, a kettle and several pots, along with a variety of pot hooks and trivets. In the American colonies, these items would commonly be produced by a local blacksmith from iron while brass or copper vessels were common in Europe and Asia. Improvements in metallurgy during the 19th and 20th centuries allowed for pots and pans from metals such as steel, stainless steel and aluminum to be economically produced.
Metal
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| Cookware materials |
Metal pots are made from a narrow range of metals because pots and pans need to conduct heat well, but also need to be chemically unreactive so that they do not alter the flavor of the food. Most materials that are conductive enough to heat evenly are too reactive to use in food preparation. In some cases (copper pots, for example), a pot may be made out of a more reactive metal, and then tinned or clad with another.
Aluminum
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| An anodized aluminum saute pan |
Aluminum is a lightweight metal with very good thermal conductivity. It is resistant to many forms of corrosion. Aluminum is commonly available in sheet, cast, or anodized forms, and may be physically combined with other metals (see below).
Sheet aluminum is spun or stamped into form. Due to the softness of the metal it may be alloyed with magnesium, copper, or bronze to increase its strength. Sheet aluminum is commonly used for baking sheets, pie plates, and cake or muffin pans. Deep or shallow pots may be formed from sheet aluminum.
Cast aluminum can produce a thicker product than sheet aluminum, and is appropriate for irregular shapes and thicknesses. Due to the microscopic pores caused by the casting process, cast aluminum has a lower thermal conductivity than sheet aluminum, and is more expensive. Accordingly, cast aluminum cookware has become less common. It is used for Dutch ovens, heavyweight baking pans such as bundt pans, and wares such as ladles or handles where low thermal conductivity is desired.
Anodized aluminum has had the naturally occurring layer of aluminum oxide thickened by an electrolytic process to create a surface that is hard and non-reactive. It is used for sauté pans, stockpots, roasters, and Dutch ovens.
Uncoated and un-anodized aluminum can react with acidic foods to change the taste of the food. Sauces containing egg yolks, or vegetables such as asparagus or artichokes may cause oxidation of non-anodized aluminum.
Aluminum exposure has been suggested as a risk factor for neurodegenerative diseases such as Alzheimer's disease. The Rondeau, Commenges et al. article cited below states "These findings support the hypothesis that aluminum in drinking water is a risk factor for AD." (Alzheimer's disease)". The Alzheimer's Association states that "studies have failed to confirm any role for aluminum in causing Alzheimer's. [Today] few experts believe that everyday sources of aluminum pose any threat."According to Dr. Morton Walker on page 98 of his 1994 book Toxic Metal Syndrome: How Metal Poisonings Can Affect Your Brain, the Alzhhimer's Association has accepted funding from major players in the aluminum industry.
In classical Western cooking, pots are formed with thick copper sheets with a thin inner layer of tin. The copper provides the best thermal conductivity of common metals and therefore results in even heating. Copper is reactive with acidic foods, discovered with the discovery of tomatoes in the new world and subsequent introduction to old world copper pots. The tin lining prevents the copper from reacting with acidic foods. The products resulting from the reaction causes copper toxicity. The lead-free and cadmium-free tin lining is susceptible to tin pest. In some cases unlined copper is desirable, for instance in the preparation of meringues and foams. Copper pots are expensive and require retinning, and when made with thick copper plates are heavy. With modern metallurgical techniques, such as cladding, copper is incorporated into the constructions of cookware, often as an enclosed heat spreading disk .
Cast iron cookware
Cast iron cookware is slow to heat, but once at temperature provides even heating. Cast iron can also withstand very high temperatures, making cast iron pans ideal for searing. Being a reactive material, cast iron can have chemical reactions with high acid foods such as wine or tomatoes. In addition, some foods (such as spinach) cooked on bare cast iron will turn black.
Cast iron is a porous material that rusts easily. As a result, it typically requires seasoning before use. Seasoning creates a thin layer of oxidized fat over the iron that coats and protects the surface, and prevents sticking.
Enameled cast iron cookware was developed by Le Creuset. In 1934, Le Creuset also solved the problem of excessive evaporation and scorching when using the cast iron Dutch ovens during cooking, by creating the enameled cast iron doufeu.
Stainless Steel
Stainless steel is an iron alloy containing a minimum of 11.5% chromium. Blends containing 18% chromium with either 8% nickel,called 18/8, or with 10% nickel, called 18/10, are commonly used for kitchen equipment. Stainless steel's virtues are resistance to corrosion, non-reactivity with either alkaline or acidic foods, and resistance to scratching and denting. Stainless steel's drawbacks for cooking use is that it is a relatively poor heat conductor and contains chromium; a toxic metal considered unsafe when ingested as metal particles. Since the material does not adequately spread the heat itself, stainless steel cookware is generally made with a disk of copper or aluminum in or on the base to conduct the heat across the base.
Carbon Steel
Carbon steel cookware can be rolled or hammered into very thin sheets of material, while still maintaining high strength and heat resistance. This allows for rapid and high heating. Carbon steel does not conduct heat as well as other materials, but this may be an advantage for woks and paella pans, where one portion of the pan is intentionally kept at a different temperature than the rest. Like cast iron, carbon steel must be seasoned before use. Rub a fat (lard is recommended) on the cooking surface only and heat the cookware over the stovetop. The process can be repeated if needed. Over time, the cooking surface will become dark and nonstick. Carbon steel is often used for woks and crêpe pans.
Enameled cast iron
Enameled cast iron cooking vessels are made of cast iron covered with a porcelain surface. This creates a piece that has the heat distribution and retention properties of cast iron combined with a non-reactive, low-stick surface.
Enamel over steel
The enamel over steel technique creates a piece that has the heat distribution of carbon steel and a non-reactive, low-stick surface. Such pots are much lighter than most other pots of similar size, are cheaper to make than stainless steel pots, and do not have the rust and reactivity issues of cast iron or carbon steel.[citation needed] Enamel over steel is ideal for large stockpots and for other large pans used mostly for water-based cooking. Because of its light weight and easy cleanup, enamel over steel is also popular for cookware used while camping.
Clad aluminum or copper
Cladding is a technique for fabricating pans with a layer of heat conducting material, such as copper or aluminum, covered by a non-reactive material, such as stainless steel. Rather than just a heat-distributing disk on the base, the copper or aluminum extends over the entire pan.
Aluminum pans are typically clad on both their inside and the outside surfaces, providing both a stainless cooking surface and a stainless surface to contact the cooktop. Copper is typically clad on its interior surface only, leaving the more attractive copper exposed on the outside of the pan.
Some high-end cookware uses a dual-clad process, with a thin stainless layer on the cooking surface, a thick core of aluminum to provide structure and heat diffusion, and a thin layer of copper on the outside of the pot that provides additional diffusion and the "look" of a copper pot. This provides much of the functionality of tinned-copper pots for a fraction of the price.
Teflon coated frying pan
Non-stick
Steel or aluminum cooking pans can be coated with a substance such as polytetrafluoroethylene (PTFE) in order to minimize food sticking to the pan surface.
There are advantages and disadvantages to such a coating. Coated pans are easier to clean than most non-coated pans, and require little or no additional oil or fat to prevent sticking.
On the other hand, some sticking is needed to cause sucs to form, so a non-stick pan cannot be used where e.g. a pan sauce is desired. And non-stick pans must not be overheated (see below). Nonstick coatings tend to degrade over time. In order to preserve the coating, it is important never to use metal implements or harsh scouring pads or chemical abrasives when cleaning.
There is a potential danger in the use of PTFE-based coatings: while decomposition of the coating does not occur at normal cooking temperatures (below about 465 °F/240 °C), overheating can produce decomposition products that are toxic to humans and fatal to birds. Unfortunately, overheating is relatively easy.Fortunately, there are alternatives such as seasoned or enameled cast iron.
The main difference in quality levels of the coatings is in the formulas of the liquid coating, the thickness of each layer and the number of layers used. Higher quality nonsticks use powdered ceramic or titanium mixed in with the nonstick to strengthen them and to make them more resistant to abrasion and deterioration. Some nonstick coatings contain hardening agents. Some coatings are high enough in quality that they pass the strict standards of the National Sanitation Foundation for approval for restaurant use.
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