Sodium aluminium phosphate (SAlP) are sodium salts of aluminium phosphates. They are

inorganic An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds⁠that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemistry''. Inor ...

and most commonly have the formulas NaH₁₄Al₃(PO₄)₈·4H₂O and Na₃H₁₅Al₂(PO₄)₈.Klaus Schrödter, Gerhard Bettermann, Thomas Staffel, Friedrich Wahl, Thomas Klein, Thomas Hofmann "Phosphoric Acid and Phosphates" in ''Ullmann’s Encyclopedia of Industrial Chemistry'' 2008, Wiley-VCH, Weinheim. These materials are prepared by combining alumina,

phosphoric acid Phosphoric acid (orthophosphoric acid, monophosphoric acid or phosphoric(V) acid) is a colorless, odorless phosphorus-containing solid, and inorganic compound with the chemical formula . It is commonly encountered as an 85% aqueous solution, ...

, and

sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula . It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly corrosive base (chemistry), ...

."Phosphoric Acids and Phosphates" David R. Gard, 2005, Wiley-VCH. In addition to the usual hydrate, an anhydrous SAlP is also known, Na₃H₁₅Al₂(PO₄)₈ (CAS#10279-59-1), referred to as 8:2:3, reflecting the ratio of phosphate to aluminium to sodium. Additionally an SAlP of ill-defined stoichiometry is used (Na_''x''Al_''y''(PO₄)_''z'' (CAS# 7785-88-8). The acidic sodium aluminium phosphates are used as acids for baking powders for the chemical leavening of baked goods. Upon heating, SAlP combines with the baking soda to give

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

. Most of its action occurs at baking temperatures, rather than when the dough or batter is mixed at room temperature. SAlPs are advantageous because they impart a neutral flavor. As a

food additive Food additives are substances added to food to preserve flavor or enhance taste, appearance, or other sensory qualities. Some additives, such as vinegar ( pickling), salt ( salting), smoke ( smoking) and sugar ( crystallization), have been used f ...

, it has the

E number E numbers, short for Europe numbers, are codes for substances used as food additives, including those found naturally in many foods, such as vitamin C, for use within the European Union (EU) and European Free Trade Association (EFTA). Commonly ...

E541. Basic sodium aluminium phosphates are also known, e.g., Na₁₅Al₃(PO₄)₈. These species are useful in cheese making.

References

{{Phosphates Sodium compounds Aluminium compounds Phosphates E-number additives