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|Section2= |Section3= |Section7= |Section8= }} Disodium pyrophosphate or sodium acid pyrophosphate is an inorganic compound consisting of sodium cations and pyrophosphate anion. It is a white, water-soluble solid that serves as a buffering and chelating agent, with many applications in the food industry. When crystallised from water, it forms a hexahydrate, but it dehydrates above room temperature. Pyrophosphate is a polyvalent anion with a high affinity for polyvalent cations, e.g. Ca2+. Disodium pyrophosphate is produced by heating sodium dihydrogen phosphate: :2 NaH2PO4 → Na2H2P2O7 + H2O ==Food uses== Disodium pyrophosphate is a popular leavening agent found in baking powders. It combines with sodium bicarbonate to release carbon dioxide: : Na2H2P2O7 + NaHCO3 → Na3HP2O7 + CO2 + H2O It is available in a variety of grades that affect the speed of its action. Because the resulting phosphate residue has an off-taste, SAPP is usually used in very sweet cakes which mask the off-taste.〔John Brodie, John Godber "Bakery Processes, Chemical Leavening Agents" in Kirk-Othmer Encyclopedia of Chemical Technology 2001, John Wiley & Sons. 〕 It is designated in the United States as generally recognized as safe (GRAS) for food use. It is used in canned seafood to maintain color and reduce purge during retorting. Retorting achieves microbial stability with heat.〔() -Retorting, Accessed 2010-11-27〕 It is an acid source for reaction with baking soda to leaven baked goods. In baking powder, it is often labeled as food additive E450.〔()〕 In cured meats, it speeds the conversion of sodium nitrite to nitrite (NO2−) by forming the nitrous acid (HONO) intermediate, and can improve water-holding capacity. Disodium pyrophosphate is also found in frozen hash browns and other potato products, where it is used to keep the color of the potatoes from darkening.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Disodium pyrophosphate」の詳細全文を読む スポンサード リンク
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