Experimental cookery

Phosphate powders. Three phosphate compounds are or have been used In baking powder. Monosodium phosphate has been used, but so far as the author knows no baking powders on the market at present contain it. Monocalcium phosphate is most frequently used. Lately sodium acid pyro- phosphate is being used in considerable quantities by commercial bakers. Phosphoric acid forms three series of salts, such as Na3P04, NaoHP04, and NaH2P04. The first is not formed in baked products. Davis and Maveety state that the monosodium phosphate (NaH2P04), disodium phosphate (NaoHP04), tricalcium phosphate (Ca3(P04)2), and dical- cium phosphate (CaHP04) are found in the residue after the baking powder has reacted. They state that the reaction is carried to completion with the formation of Na2HP04 and Ca3(P04)2 only when an excess of hydroxyl ions is present. Bailey gives three equations which represent the reactions that may take place under favorable conditions. He adds that equation (3) represents what probably usually occurs. 2CaH4(P04)2 + 4NaHC03 > 2CaHP04 + 2Na2HP04 + 4CO2 4- 4H2O (1) 3CaH4(P04)2 4- 4NaHC03 > Ca3(P04)2 4- 4NaH2P04 + 4CO2 + 4H2O (2) 3CaH4(P04)2 4- SNaHCOs > Ca3(P04)2 + 4Na2HP04 + 8CO2 4- 8H0O (3) With sodium acid pyrophosphate Bailey states that there is some ques- tion concerning the products of reaction and gives two equations that may represent what occurs. Na2H2P207 4- 2NaHC03 > 2Na2HP04 4- 2CO2 4- H2O and Na2H2P207 4- 2NaHC03 > Na4P207 4- 2CO2 4- 2H2O 452 BATTERS AND DOUGHS Sodium acid pyrophosphate is at present put up with cornstarch and sold only to bakers. The bakers add the soda, using 2 parts of combined starch and disodium pyrophosphate to 1 part of soda. This proportion yields about 17 per cent of available carbon dioxide. Some of the other baking powders for the bakery trade are also made to yield 17 per cent of carbon dioxide. Sulfate powders. The author knows of no straight sulfate powders on the market at the present time. Sodium aluminum sulfate is the acid salt used in these powders. Combination sulfate-phosphate powders. These powders contain two acid salts in varying proportions. The sulfate salt is sodium aluminum sulfate and the phosphate is monocalcium phosphate. Hart states that sodium aluminum sulfate "has first class keeping quality and has an aerating value about the same as tartartic acid." The reaction of the phosphate salt with soda has been given above. One ingredient of the residue of sulfate powders is aluminum hydroxide. Another is sodium sulfate. The latter in excess produces a bitter taste. The sodium aluminum sulfate is first hydrolyzed with water. The sulfuric acid formed then reacts with the sodium bicar- bonate. Bailey states that ''Besides the reaction of the phosphate and sodium Na2S04 Al2(S04)3 + 6H2O > Na2S04 + 2A1(0H)3 + 3H2SO4 3H2SO4 + 6NaHC03 > 6CO2 + 6H2O + 3Na2S04 aluminum sulfate with soda, there is probably an interaction between the two." The preceding Graphic Chart by Dr. Chittick shows *'the ingredients present in the various types of baking powders, proportioned to produce 14 per cent of gas, which is the average strength of the standard baking powders." It also shows the compounds formed from the reaction of the various baking powders and the percentage or possible percentage of these compounds.