35 TRANSACTIONS OF WAGNER 



THE CHEMISTRY OF BREAD-MAKING 



potassium salt was replaced by that of sodium, NaHCOs, which was called "soda 

 saleratus," and is now extensively used under the name of "baking soda." 

 This compound (and also its predecessor, the potassium salt) was at first em- 

 ployed and is still used in all homes, with certain acid liquids used in the prep- 

 aration of the dough. These acid liquids are molasses, used in the prepara- 

 tion of cake but not of bread, and sour milk, used in cakes, biscuits, or bread. 

 Cream of tartar is also used in the kitchen as a factor for decomposing baking 

 soda and will be referred to under the baking-powder containing it. The 

 acids of molasses are the natural acids of the sugar-cane juice plus a small 

 amount resulting from alteration during its handHng. There being no single 

 predominating acid, it is not possible to write a simple reaction for the de- 

 composition of sodium bicarbonate by molasses. Whatever acids there are 

 yield the carbon dioxid by a decomposition analogous to any of those given 

 below. The acid of sour milk is lactic acid, which has the empirical formula 

 HC3H5O3. The reaction between this and sodium acid carbonate is : 



The leavening effect is produced by the carbon dioxid. The sodium lactate 

 resulting from the reaction remains in the baked product in greater or lesser 

 amount, depending upon the acidity of the milk and the amount of sodium 

 bicarbonate which has been used. The lactic acid of sour milk, like the hydro- 

 chloric acid previously referred to, does not exist in an}^ soHd form of stable 

 character, and is, therefore, not available for use in a baking-powder. 



In the empirical or home use of saleratus or baking soda as a leavening 

 agent with decomposing factors of doubtful or var^dng acidity, as have been 

 described, it sometimes results that the alkaline compound is present in sKght 

 excess. When this is the case, the baked product possesses what is called a 

 "soda taste," disagreeable to most persons and which is due to the decomposing 

 influence of heat and moisture upon the sodium acid carbonate, converting it 

 into sodium carbonate according to the following reaction: 



2NaHC03-> Na2C03 + H2O ^- CO2. 



This condition never occurs with manufactured baking-powder, as the in- 

 gredients are so calculated as to produce exact neutralization or leave a sHght 

 trace of the acidic element. 



