Metals and Conductivity

Kind of metal. Different metals have different conductivity, or the speed at which they transfer or disperse heat. The following materials are used for cooking equipment:

• Aluminum is used for most cooking utensils in food-service kitchens. It is a good conductor, and its light weight makes pots and pans easy to handle. Because it is a relatively soft metal, it should not be banged around or abused.

  Do not use aluminum for storage or for long cooking of strong acids because it reacts chemically with many foods. Also, it tends to discolor light-colored foods such as sauces, especially if they are stirred or beaten with a metal spoon or whip.

  Pans made of anodized aluminum, sold under such brand names as Calphalon, have surfaces that are harder and more corrosion-resistant than regular aluminum pans. Although this is not, strictly speaking, a nonstick finish, it is less porous than untreated aluminum, so foods are less likely to stick. Also, it is more resistant to acids than regular aluminum, and it will not discolor light-colored foods. Its disadvantages are that it is more expensive than and not quite as durable as standard aluminum.

  Aluminum, of course, cannot be used on induction cooktops, which work only with steel or iron.

• Copper, the best heat conductor of all, was once widely used for cooking utensils. However, it is extremely expensive and requires a great deal of care. In addition, it is heavy. Today it is used mostly for show, although a few high-end restaurants use it for cooking as well.

  Copper reacts chemically with many foods to create poisonous compounds, so copper pans must be lined with another metal, such as tin or stainless steel.

• Stainless steel is a poor heat conductor. Cooking pots and pans made of it tend to scorch foods easily because the heat does not disperse throughout the pan quickly and evenly. Stainless steel is ideal for storage containers because it does not react with foods as aluminum does. It is also used for low-temperature cooking or holding equipment, such as steamer pans and counter pans, where scorching or hot spots are not a problem.

  Stainless-steel pots and pans are available with a heavy layer of copper or aluminum bonded to the bottom. Heavy aluminum pans may also be lined with stainless steel on the inside, or on both the inside and outside. This feature gives the advantages of stainless steel (hardness, durability, nonreactivity with acid foods, and nondiscoloration of light sauces) with the heat-conducting qualities of copper or aluminum. These pans are usually expensive.

• Cast iron is a favorite material with many chefs because of its ability to distribute heat evenly and to maintain high temperatures for long periods. It is used in griddles and heavy skillets. Cast iron cracks easily if dropped. It rusts quickly unless kept properly conditioned and dry.
• Porcelain enamel-lined pans should not be used. In fact, they are forbidden by some health departments. They scratch and chip easily, providing good hiding places for bacteria. Also, certain kinds of gray enamel can cause food poisoning if chipped.

• Nonstick plastic-type coatings, known by brand names including Teflon and Silverstone, provide a slippery finish, but one that requires a lot of care because it is easily scratched. Do not use metal spoons or spatulas with this equipment. Instead, use tools made of plastic, silicone, or wood. Do not use abrasive materials to clean the nonstick surface.

  Nonstick pans are best reserved for eggs and other items that are likely to be damaged if they stick. Many chefs keep a set of nonstick egg pans and use them for no other purpose. In addition, these pans are useful for dietary cooking because they enable cooks to sauté foods with little or no added fat.

  Nonstick coatings should not be used for sautéing and braising procedures that involve deglazing to make a sauce. Foods do not brown as well in nonstick pans as in traditional metal pans, and they do not form a fond (the flavorful browned bits that stick to the pan) that can be deglazed to make a sauce or braising liquid.

• Glass and earthenware have limited use in commercial kitchens because they break easily. They are poor conductors of heat but are resistant to corrosion and food acids.