On food and cooking the science and lore of the kitchen ( PDFDrive ) 1489

steel pans improve their easily corroded surface by building up an artificial protective layer They “season” them by coating them with cooking oil and heating them for several hours The oil penetrates into the pores and fissures of the metal, sealing it from the attack of air and water And the combination of heat, metal, and air oxidizes the fatty acid chains and encourages them to bond to each other (“polymerize”) to form a dense, hard, dry layer (just as linseed and other “drying oils” doon wood and on paintings) Highly unsaturated oils — soy oil, corn oil — are especially prone to oxidation and polymerizing To avoid removing the protective oil layer, cooks carefully clean seasoned cast iron pans with mild soaps and a dissolving abrasive like salt, rather then with detergents and scouring pads Stainless Steel The important exception to the rule that metals form protective surface coatings is iron, which rusts in the presence of air and moisture The orange complex of ferric oxide and water (Fe2O3• 2O) is a loose powder rather than a continuous film, and so does not protect the metal surface from further contact with the air Unless it’s protected by some other means, iron metal will corrode continuously (this is why pure iron is not found in nature) Efforts to make this cheap and abundant element more resistant to rusting resulted in the 19th century in the development of stainless steel, an iron-carbon alloy that — in cookware — is formulated with about 18% chromium and 8–10% nickel Chrome is synonymous with bright and permanent shininess because chromium is extremely prone to oxidation and naturally forms a thick protective oxide coat In the stainless steel mixture, oxygen reacts preferentially with the chromium atoms at the .. .The important exception to the rule that metals form protective surface coatings is iron, which rusts in the presence of air and moisture The orange complex of ferric oxide and water (Fe2O3•... 2O) is a loose powder rather than a continuous film, and so does not protect the metal surface from further contact with the air Unless it’s protected by some other means, iron metal will corrode continuously (this is why pure iron is not... continuously (this is why pure iron is not found in nature) Efforts to make this cheap and abundant element more resistant to rusting resulted in the 19th century in the development of stainless steel, an iron-carbon alloy that — in cookware — is formulated