In yeast-raised cakes the binding quality of the different ingredients vary, and one egg, for instance, only possesses the binding quality for one and one-half ounces of corresponding material; but, on the other side, the flour will absorb and retain a good deal more moisture for the reason that for yeast-raised cakes stronger flour is used than for cakes made by the use of baking powders, and again during the process of fermentation the gluten is developed, whereas in baking powder goods the gluten in flour is of no value.
It is needless to repeat here that baking powder and allied products are of entirely different nature and quality, and the comparison is not made with intention to substitute one leavening agent for the other.
Baking powders, ammonia carbonate, soda bicarbonate, cream of tartar, etc., do not add to the nutritious quality of a cake, but their use is tolerated by reason of their great convenience, and, furthermore, they are an absolute necessity for a certain class of cakes, but in all cases good judgment should be exercised to use the least possible quantities that will produce the necessary lightness or neutralize the presence of acidity.
The amount of soda bicarbonate to be used, especially for molasses goods, often depends upon the water, and while the latter is little used in the manufacture of cakes, it is well to state that soft water requires less soda than if hard water is to be used. Hard water may be softened by the addition of a solution of soda bicarbonate.
Sodium chloride, generally called common salt, is very rarely used in the manufacture of cakes, unless for molasses goods, etc., where the addition of a minute amount exerts a beneficial influence on the binding material employed; it also acts, in part, to neutralize the acidity of molasses, which usually is contained in the latter in overabundant quantities, and, therefore, does not interfere with the action of the soda bicarbonate. The principal reason for using a small amount of salt is that it will stimulate the capacity of the palate to recognize the flavor of the finished product to better advantage.
Sodium bicarbonate, commonly called baking soda, is used to spread and lighten the cakes, as well as for its neutralizing power, as in contact with acids it develops carbonic acid gas, thus leavening the cakes.
Ammonia carbonate is the strongest of this class of leavenings known in the manufacture of cakes, but leaves a displeasing flavor and coarse grain if used in too large quantities; employed in part with soda bicarbonate it usually gives very satisfactory results.
If by error too much soda bicarbonate is used, the product will have a greenish tint and bitter taste. If such error occurs, it is well to add a proportion of cream of tartar or tartaric acid to neutralize the over-amount of soda and allow the mixture to rest sufficient time so one may neutralize the other.
It is hardly necessary to refer to the flour, as every one connected with the baking business knows that soft flour is used for cakes—one containing the least gluten, and consists usually of the soft white winter wheat class. While winter wheat flour often can be bought at a lower price than spring wheat flour, it is not the reason for its use in cakes, but because it is better adapted.