Cookware Training Information
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Cookware is a product that we use almost on a daily basis, without thinking much about it. However, with the proliferation of brands, base metals, interior coatings, exterior finishes, and claims made by various manufacturers, a consumer shopping for new cookware can easily become very confused in their shopping experience. Often salespeople in retail stores are not conversant with the different properties of various metals and other materials used in cookware, and the advantages and disadvantages of each.
This information is intended to explain the differences in today's products in a simple manner, and to serve as a general background for those who are interested in some of the technical aspects of cookware construction and manufacturing. This information may be helpful in your final purchase decision. If you have any questions that are not answered in the information that follows, please feel free to contact us with your question through e-mail or give us a call.
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Cookware Materials
STAINLESS STEEL - 18/0 VS. 18/8
Stainless steel is an alloy that starts with basic iron with up to 8 alloys added, depending on the quality. The major alloys in stainless steel are chromium and nickel. The chromium provides rust and corrosion resistance and durability. Nickel provides additional rust resistance, hardness, and high polishing characteristics.
The numbers 18/0 and 18/8 refer to the percentage of content of chromium and nickel. To be classified as stainless steel, the metal must contain at least 11 % chromium (no nickel required). Stainless steel used in cookware is normally 18% chromium and 8% to 10% nickel (300 series).
Low end stainless steel cookware, mixing bowls, stockpots and accessories are usually 18/0, (400 series) which are usually not highly polished, and could be subject to some rust spotting.
A simple way to test whether or not a stainless steel pan is 18/0 or 18/8 is to place a magnet against it. If the pan is magnetic, it is 18/0...if not, it is 18/8 (or 18/10). The addition of nickel neutralizes the natural ferrous properties of the iron in the stainless steel.
All of the stainless steel cookware offered by Innova Inc. is made of the highest quality 18/10 material, and all pieces go through 18 polishing steps in the finishing process.
ALUMINUM - TYPES OF ALUMINUM COOKWARE
Aluminum cookware can be formed either by pressing or by casting. Most aluminum cookware on the market today is formed by pressing. Casting of aluminum is a slower and more expensive process, however the end result is that the body thickness is generally thicker than pressed aluminum, and the bottom and the rims can be made even thicker than the sidewalls, which helps prevent warping or going "out of round". Cast aluminum is also more porous than pressed aluminum, which results in better heat retention. When polished or coated, it is difficult to visually tell the difference between pressed or cast aluminum.
Aluminum cookware can also be improved by a process called "hard anodizing". This is a Electro-chemical process which increases the thickness of natural oxide film in aluminum, to give it a hard non-oxidizing finish. The surface of the aluminum actually becomes harder than steel, which dramatically increases the durability of the surfaces of aluminum. The exterior finish after the hard anodizing process turns to a dark gray color. For information on our hard anodized aluminum line, refer to "Confidence" cookware in the product information section.
COPPER
Copper, alone or in an alloyed form, has been used in cooking utensils almost since the dawn of history. Copper's uniform heat conductivity makes it a good material for top-of-range cooking because the heat is distributed evenly. This property also enables copper serving utensils to keep foods warm and palatable.
Copper cooking surfaces are usually lined with tin, nickel, or stainless steel for two reasons:
1. Copper will react to foods with a high acid content, which in some cases could be toxic.
2. Cooked foods left directly in contact with uncoated copper may become discolored. While it is not necessarily injurious to health, the discoloration tends to detract from the food's eye appeal.
Tin or nickel linings are not very durable, and therefore should be recoated if these surfaces wear thru to the copper on the inside of the pan.
Another manufacturing process bonds or laminates copper to stainless steel or other metals. A core of solid copper sandwiched between two layers of stainless steel is another way copper is used to distribute heat uniformly.
CAST IRON
Cast iron cooking utensils have been with us for thousands of years, going back to ancient China.
In Europe during the Middle Ages, cast iron utensils were considered so valuable that they were listed along with gold, jewels, and other riches of royalty. An iron foundry, where utensils and other cast iron products were manufactured, was one of the first industries organized in North America.
Today's cast iron utensils have been improved greatly over those of even the recent past. They are made of iron alloys that give additional strength to the utensil. And today there are cast iron utensils with colorful porcelain enamel exterior and interior finishes.
Cast iron currently is used for utensils that include skillets, roasters and Dutch ovens, broilers, griddles, and some specialty items, such as muffin and corn bread pans. These utensils are excellent for browning, frying, stewing and baking foods.
PORCELAIN ON STEEL
Porcelain enamel is essentially a highly durable glass which, with coloring oxides and other inorganic materials, is fused to metal at extremely high temperatures. It first found its way into the kitchen as a decorative finish for wood-burning ranges and cast iron utensils. Later, when techniques were discovered for applying it to sheet steel, it became a standard coating for coffee pots, roasting pans, and saucepans.
In the manufacture of cooking utensils, porcelain enamel is applied after the metal is formed into its final shape. It can be applied to carbon steel, aluminum, stainless steel, and cast iron.
It is one of the most versatile finishes, offering virtually an unlimited range of colors and design effects. Today's colors include many shades of bright reds, vibrant greens, clear blues, sunny yellows, and warm oranges, as well as earth tones. Plaids, stripes, decorator designs, and even provincial prints can be found. There are also decorative porcelain decals, mechanically applied that have the same scratch and stain resistant qualities of the regular porcelain coating.
GLASS, CERAMIC AND GLASS-CERAMIC
In the 20th century, heat-resistant glass and glass-ceramic were developed. Like ceramic, they meet the need for attractive ware used for mixing, cooking, serving, and storing. Major features are attractiveness, one-dish convenience, and inert non-porous surfaces that won't absorb food odors or flavors. For easy cleaning, both glass and ceramic ovenware are available with nonstick interiors.
While most are very rugged, they can break under impact. However, some glass, ceramic and glass-ceramic cookware manufacturers warranty their products against thermal breakage, and offer free replacement should the ware break in normal use within the warranty conditions. Heat-resistant glass cookware may be made of clear or tinted transparent material or opaque white (commonly called "opal" glass). Glass-ceramic cookware may be white or transparent and tinted. Ceramic cookware is available in white or a variety of colors.
Heat resistant glass can be used for storing, cooking and serving. Some pieces 'can be used on the rangetop, while others are suitable only for the oven. Those designed for baking can be taken from refrigerator and put into preheated ovens after the utensil reaches room temperature. As a rule, they should not be used on the rangetop or under the broiler. Heat-resistant glass rangetop products should always be used with a wire grid on an electric range but should never be taken from the refrigerator or freezer and placed directly on a hot rangetop element. Similarly sudden cooling may be harmful to glass cookware. Hot glass cookware should not be allowed to come in contact with wet countertops, nor should they be placed in water while they are still hot. Some ceramic cookware is made of heat-resistant material which can go from the freezer to a hot oven or microwave. None is suitable for top-of-range or broiler use. Like glass cookware, ceramic cookware holds heat for a long time while providing the additional benefit of an attractive serving dish. Ceramic cookware is available in a wide variety of shapes, colors, and designs.
Among the most thermally shock-resistant material ever developed by man, glass-ceramic is a true space-age material. It was first used in rocket nosecones because the glass-ceramic material could take the extreme temperature changes encountered in their supersonic flight from the earth's surface into outer space and back. Glass-ceramic cookware offers wide food preparation versatility. It can be used for rangetop cooking and is excellent for roasting, broiling or baking -in the conventional or microwave oven. It can go directly from the freezer to the rangetop, broiler or hot oven. Glass-ceramic cookware can be immersed, hot off the stove, into sudsy dishwater for easy cleanup.
TRI-PLY CONSTRUCTION
Different types of metal can be laminated or bonded together, to combine the advantages of different metals into a cookware body. An example would be a 3 layer construction consisting of two outer layers of stainless steel, with an inner layer of aluminum. Innova Inc. offers a line constructed of a copper exterior, aluminum inner layer, and a stainless steel interior, which incorporates all of the benefits of each metal into one piece of cookware. The lamination of metals is done in the raw material stage, in sheets, and blanks are cut from the sheets to be formed into cookware shapes in a press. The entire process is very costly, and this construction is found only on higher priced cookware.
Material Advantages and Disadvantages
There are a number of materials used in the cookware industry in the construction of top of range cookware. Each has advantages and disadvantages. The chart below will allow you to weigh the pros and cons of each material.
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Advantages |
Disadvantages |
Aluminum
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- |
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excellent heat conductor |
- porous and relatively soft |
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- relatively light in weight |
- dents and scratches easily |
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- difficult to clean |
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- stains easily |
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- reacts to food |
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- oxidizes to a dull gray color |
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- warps easily |
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- requires a "nonstick" coating |
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Stainless Steel
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+ |
- |
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- extremely durable |
- poor heat conductor |
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- non porous, extremely hard |
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- smooth surface, easy to clean |
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- dent and scratch resistant |
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- does not react to foods |
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- easy to maintain mirror finish |
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Cast Iron
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+ |
- |
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- relatively low cost |
- extremely heavy |
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- holds heat longer |
- rusts easily |
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- reacts to food |
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Copper
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+ |
- |
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- excellent heat conductor |
- relatively high cost |
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- reacts to food (toxic with some foods) |
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- oxidizes, very difficult to maintain finish |
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- dents and scratches easily |
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- must be lined with tin, nickel, or stainless steel |
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Enameled Steel
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+ |
- |
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- colorful, fashionable |
- very poor heat conductor |
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- chips easily |
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- rusts easily when chipped |
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Carbon Steel
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+ |
- |
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- low cost |
- very poor heat conductor |
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- rusts easily |
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Glass
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+ |
- |
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- can be decorated or plain |
- extremely poor heat conductor |
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- heat resistant if tempered |
Cookware Coatings
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NON STICK COATINGS
Coatings used in the cookware industry are made from either a silicone base or a fluorocarbon (P.T.F.E.) base. Fluorocarbon coatings are applied in a 2 or 3 coat process, consisting of 1 or 2 layers of the non-stick material, plus a "sealer" or topcoat. This is the process generally used on interior coating. Exterior coatings are usually use a 1 coat silicone based process, since fluorocarbons have a drawback...if accidentally overheated, the fumes will kill household birds.
The main differences in different quality levels are in the formulas of the liquid coating, the number of layers of coating, and the thickness of each layer.
"Generic" or non-branded coatings are generally used on low end frypans, and will usually be a formula that has less durability and release qualities than branded coatings.
REINFORCED NONSTICK COATINGS
A reinforced coating is one that utilizes the application of stainless steel particles in a molten state to the surface of the pan prior to coating with the nonstick material. This technology was pioneered, developed, and refined by Whitford Corporation. The reinforced "Excalibur" coating system is the result of twenty years of research and development that required constant trial and error, which led to small but important changes in the basic concept of a reinforced nonstick until the ideal was finally achieved.
These are the basic differences between Excalibur and other "reinforced" nonsticks:
- The Excalibur alloy:
Excalibur uses the strongest, most corrosion-resistant alloy in the stainless steel spectrum. Excalibur is the only reinforced nonstick that can use this alloy (which is protected by a Whitford patent). This means:
- Greater durability: The stainless steel spray applied to the substrate of the pot or pan forms a harder, tougher, longer-lasting base for the nonstick coatings that are applied into and over the "peaks and valleys" formed by the hardened spray. This is true whether the pan is made of stainless steel, carbon steel, cast iron or aluminum. Metal kitchen tools can be used with Excalibur.
- Greater resistance to corrosion: The unique "recipe" of elements in the Excalibur alloy provide maximum resistance to oxidation as well as to galvanic corrosion.
- Adhesion:
Excalibur provides superior adhesion in two important ways:
- The alloy adheres better to the substrate of the pot or pan, no matter what the composition of the metal substrate.
- The special Whitford coatings specifically engineered to mate with the Excalibur alloy provide superior adhesion when compared to most 300 and 400 series of stainless steel used by other "reinforced" nonsticks.
- Uniform thickness:
The uniformity of the Excalibur product's surface not only resists abrasion better, but also provides more uniform wear over the life of the pot or pan. Raised, hard ridges, on the other hand, tend to lose their nonstick quality.
- Stain resistance:
The uniform Excalibur surface is not only easier to clean, but it is designed to avoid wells and other small depressions found in patterned surfaces that capture fats, juices, and other food residues that eventually carbonize. This not only encourages staining and spoils the aesthetics of the pan, it also deteriorates the release properties of the surface.
- Pattern vs. no pattern:
Other "reinforced" nonsticks offer a pattern pressed into the surface of the pot or pan on the theory that this will provide an anchor for the nonstick. Excalibur research proved early on that, however attractive the theory sounds, in practice it fails. That's because the artificial ridges in the surface provide hard, raised edges that are far enough apart from one another to become easy targets. When metal utensils are used, they simply scrape the nonstick off these ridges in amounts sufficient to deteriorate significantly the release of the surface (and to lead to corrosion of the inferior alloy).
Excalibur on the other hand, forms a series of "peaks and valleys" so close together that a metal spatula, by definition considerably thinker than the distance between "peaks", cannot penetrate what is essentially a uniform surface. This distributes the "attack" of the utensil over a wider, smoother surface, deflecting it and protecting the coating. The worst that can happen is that microscopic bits of nonstick are scraped off a few of the tiny peaks.
These are the basic differences between Excalibur and other "reinforced" nonsticks. For information on our commercial quality frypans with Excalibur, refer to Leyse Professional Cookware under Aluminum Cookware in the product information section. Product Information Whitford Corporation has recently developed a new method or reinforcing a nonstick coating internally, rather than externally, like Excalibur. The new coating system is called Quantum®. Rather than the external stainless steel reinforcement of Excalibur, Quantum® uses an internal reinforcement of inorganic materials with a diverse, controlled blend of particle geometries. The quantity and blend of particle shapes were developed to provide the optimum reinforcement and hardness of the coating system. Because the reinforcing components are primarily in the base coat, additional release ingredients can be incorporated into the subsequent coats to provide an unsurpassed combination of durability and nonstick food release properties. The key characteristics of the new Quantum® system are:
- Outstanding resistance to abrasion: second only to Excalibur for durability. Metal kitchen tools can be used with Quantum®.
- Excellent release: superior nonstick performance.
- Superb adhesion: won't peel or lift from the cookware surface.
- Smooth surface appearance
- High gloss
HEAT CONDUCTIVITY
Materials used in cookware vary greatly in their heat distribution properties. Stainless steel by itself is not a good conductor of heat, which is the reason that aluminum or copper is bonded to the bottom. There are methods by which raw materials can be laminated together in sheets (such as 2 layers of stainless steel with a layer of aluminum in between), for cookware manufacturing, however, this process is extremely expensive.
GAUGES
Gauge refers to the thickness of the metal. Metal thickness can be stated in inches (thousandths), millimeters, or gauge.
In the cookware industry, aluminum cookware is usually stated in gauges. The point to remember in this terminology is: the lower the number, the thicker the metal. Most stamped aluminum cookware in the mass market is 10 gauge on frypans and a thinner 12 gauge on saucepans and dutch oven. Better quality aluminum cookware would use a heavier 8 gauge on frypans and 10 gauge on other pieces. Cast aluminum cookware is equivalent to 6 gauge. Consumers are trading up to more durable open stock frypans in recent years - either 6 gauge or a very heavy 4 gauge.
Promotional lightweight frypans with "generic" non-stick coatings are usually 12 gauge or 14 gauge.
In stainless steel cookware, the thickness is generally referred to in millimeters, perhaps because of the influence of imports in this category. The standard for top of range stainless steel cookware is 0.6 MM for bodies and lids. Premium department store brands will have stainless steel bodies and lids in the range of 0.7 MM to 1.0 MM thick. Low end stainless steel cookware and low end mixing bowls and accessories are generally 0.5 MM thick.
If the cookware has an aluminum sandwich bottom, the aluminum is usually 3.0 MM thick, with a 0.5 MM stainless steel protector plate. In the case of a copper sandwich bottom, the copper thickness will vary from 1.0 MM to 2.0 MM, depending on the brand. In the case of some copper bottom cookware, the copper on the bottom is not a disk - it is applied by dipping in a tank - and is very thin (less than 0.5 MM) and hardly visible in a cross sectional view. That type of copper coating is more cosmetic than functional.
Aluminum and copper sandwich bottoms normally include a stainless steel protector plate to avoid the unsightly oxidization and stains that otherwise would appear on the unfinished aluminum or copper disk. Better quality stainless steel cookware will have a "capsule" style protector plate, which wraps up the sides of the disk as well as the bottom, completely concealing the disk in stainless steel.
Thickness Tables |
| Stainless Steel |
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Aluminum |
| Millimeters |
Inches |
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Gauge |
Inches |
Millimeters |
| 0.5 |
0.0197 |
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4 |
0.204 |
5.18 |
| 0.6 |
0.0236 |
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6 |
0.162 |
4.11 |
| 0.7 |
0.0276 |
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8 |
0.128 |
3.25 |
| 0.8 |
0.0315 |
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10 |
0.102 |
2.59 |
| 0.9 |
0.0354 |
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12 |
0.081 |
2.06 |
| 1.0 |
0.0394 |
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14 |
0.064 |
1.63 |
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16 |
0.051 |
1.30 |
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18 |
0.040 |
1.02 |
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20 |
0.032 |
0.81 |
Questions & Answers
| Q |
Can metal cookware be used on glass-ceramic "smooth top" ranges? |
| A |
In general, flat-bottomed cookware that will remain flat (won't warp) throughout cooking, regardless of material, will perform well on glass-ceramic cooktops. |
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| Q |
What is heat tint? |
| A |
Heat tint is a mottled rainbow -like discoloration on stainless steel that is caused by excessive heat. Heat tint can usually be removed with a commercial stainless steel cleaner commonly found in supermarkets. |
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| Q |
What causes aluminum to discolor? Can discoloration be removed? |
| A |
In some localities water contains minerals and alkalines which may be deposited on the inside surface of aluminum pans, causing some discoloration. This does not affect the use of the utensil nor the food prepared in it. Stains or discolorations that may appear on aluminum utensils can be removed by boiling a solution of two to three tablespoons of cream of tartar, lemon juice or vinegar to each quart of water in the utensil for five to ten minutes. Then scour lightly with a soap-filled scouring pad. |
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| Q |
Can extreme temperature variations cause metal utensils to warp? |
| A |
Yes. Don't place chilled utensils over high heat or soak hot utensils in cold water. Do not begin cooking frozen foods in a hot pan. Extreme temperature changes may warp the pan because of uneven expansion and contraction of the metal. Long periods of high heat also cause metal utensils to warp. |
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| Q |
Can top of range cookware also be used in the oven? |
| A |
Cookware with phenolic (heat-resistant plastic) handles and knobs and/or with nonstick interior coatings may generally be used in a pre-heated oven up to 350 degrees F. (180 degrees Celsius) but should not be used under the oven broiler unit. Cookware with 100% metal handles can be used in the oven up to 500 degrees F. (260 degrees Celsius), but should not be used under the broiler. Cookware with wooden handles and knobs may not be recommended for oven use. Check the manufacturer's instructions before using top of range cookware in the oven. |
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| Q |
What special instructions should be followed when cooking or frying in nonstick coated utensils? |
| A |
Basically the procedures for cooking are the same rules to be followed for regular fry pans. Medium and low heats should be used. Preheat the pan for about one and one-half minutes over medium low or medium heat. Then add food and turn the heat lower. (Many meats are first browned on both sides over medium heat; then the heat is reduced to finish cooking.) High temperatures cause food residues to burn on, affecting the non-stick characteristics. |
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| Q |
Do cooking utensils have to be discarded if a handle or knob breaks? |
| A |
Most manufacturers attach handles and knobs in such a way that they can be easily replaced. It is suggested that the specific manufacturer be contacted for replacement parts should the consumer choose to replace a damaged part rather than discard the utensil. Glass or glass-ceramic utensils that are chipped or cracked should be discarded. |
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| Q |
What is meant by heat absorption? |
| A |
Heat absorption is the transferring of heat from the air and vapor to the food. The food absorbs heat from the vapor around it. In addition, where the food is in contact with the cookware, heat transfer by conduction also occurs. |
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| Q |
What is meant by "clad?" |
| A |
"Clad" usually means the bonding of one metal to the surface of another, such as copper or aluminum to stainless steel, in a way that takes advantage of characteristics of both metals. For instance, copper or aluminum may be bonded to the exterior of stainless steel to improve heat conductivity. while the inside surface retains the easy-to-clean, scratch-resistant properties of stainless steel. |
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| Q |
What should be done before using a pan coated with a nonstick finish? |
| A |
Before using the first time, wash the utensil with hot sudsy water. Rinse thoroughly with hot water and dry immediately. Then apply a film of cooking oil or shortening to the inside surface with a cloth or paper toweling. Solid shortening is more effective than oil when greasing a bakeware pan for baking cakes. However, silicone-coated bakeware does not require pre-seasoning. |
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| Q |
Can fat or grease be used when cooking with nonstick utensils? |
| A |
Yes. Any type of solid shortening or cooking oil may be used when cooking with nonstick utensils. Except for eggs and baked goods with a high sugar content, no shortening or oil is needed to keep food from sticking. This is a definite advantage to people on low-fat diets. |
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| Q |
Do special kitchen tools have to be used with nonstick cookware and bakeware? |
| A |
Nonstick finishes on some pans may be marred by the sharp edge of a spatula or the point of a fork. For this reason, follow manufacturer's instructions as to the type of kitchen tools to be used on a nonstick utensil. Some reinforced nonstick coatings such as Excalibur and Quantum permit the use of metal utensils, however cutting with a knife is not recommended. |
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| Q |
Can cookware and bakeware be washed in an automatic dishwasher? |
| A |
Most cookware and bakeware can be cleaned safely in an automatic dishwasher. However, water with high mineral content, as well as certain detergents can darken some surfaces, stain aluminum or copper, and remove the "seasoning" from cast iron and from nonstick surfaces. Hard anodized aluminum will discolor in a dishwasher. Check the manufacturers instructions before washing your utensils in an automatic dishwasher. |
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| Q |
Is there a health hazard in using pans with a nonstick finish? |
| A |
No. Food and Drug Administration scientists have confirmed that these coatings are safe for human use. |
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| Q |
How should a utensil with a nonstick finish be cleaned? |
| A |
Wash it in hot sudsy water, using a nylon scrubber. Most nonstick finishes are dishwasher-safe. Re-conditioning with a light application of cooking oil is recommended after dishwasher use. |
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