On food and cooking the science and lore of the kitchen ( PDFDrive ) 1486

never found in nature in the pure state, and a good method for separating the metal from its ore wasn’t developed until 1890 In cookware, it is usually alloyed with small amounts of manganese and sometimes copper Aluminum’s prime advantages are its relatively low cost, a heat conductivity second only to copper’s, and a low density that makes it lightweight and easily handled Its ubiquitous presence in the form of foil wrappings and beer and soft drink cans testifies to its usefulness But because unanodized aluminum develops only a thin oxide layer, reactive food molecules — acids, alkalis, the hydrogen sulfide evolved by cooked eggs — will easily penetrate to the metal surface, and a variety of aluminum oxide and hydroxide complexes, some of them gray or black, are formed These can mar light-colored foods Today, most aluminum utensils are either given a nonstick coating or are anodized, a process that involves making the metal the positive pole (anode) in a solution of sulfuric acid, and so forcing the oxidation of its surface to make a thick protective oxide layer Nonstick Coatings and Silicone “Pans” The materials for nonstick coatings were developed around the middle of the 20th century by industrial chemists, and nonstick utensils were introduced in the 1960s Teflon and its relatives are long chains of carbon atoms with fluorine atoms projecting from the backbone They produce a plastic-like material with a smooth, slippery surface, and are as inert as ceramics at moderate cooking temperatures Above about 500ºF/250ºC, however, they decompose into a number of noxious and toxic gases Nonstick utensils therefore need to be used with care to avoid overheating The coatings have the additional disadvantage of being easily .. .the metal the positive pole (anode) in a solution of sulfuric acid, and so forcing the oxidation of its surface to make a thick protective oxide layer Nonstick Coatings and Silicone “Pans” The. .. for nonstick coatings were developed around the middle of the 20th century by industrial chemists, and nonstick utensils were introduced in the 1960s Teflon and its relatives are long chains of carbon atoms with fluorine atoms... however, they decompose into a number of noxious and toxic gases Nonstick utensils therefore need to be used with care to avoid overheating The coatings have the additional disadvantage of being