A, Class Experiment. Baking Powder.
1. Mix a little soda and cream of tartar. Does anything happen? Add water. What test with litmus paper was given by cream of tartar and water?
2. Pour a tablespoon of water on half a teaspoon of baking powder. Is gas given off? From this experiment what two substances do you suppose that baking powder contains?
3. Boil (2). When cool, add iodine. What third substance does this show is present?
4. Why starch is used.
Stir together half a teaspoon of starch and half a teaspoon of water. What becomes of the water? What happens if the soda and acid in baking powder becomes moist? Why is starch added? 5. Weigh out one ounce of soda and two and a quarter ounces of cream of tartar. Add half an ounce of starch. Mix thoroughly and sift. Compare the cost of this with the cost of an equal weight of purchased cream of tartar baking powder.
B. Prepare Sweet Milk Griddlecakes Use one-fourth of the following proportions:
The usual amount of baking powder is two teaspoons to a cup of flour. How does the amount of soda used in the sour milk griddlecake recipe compare with the amount of baking powder used here?
C. Prepare Sponge Cake.
Use one-sixth of the following recipe. Bake in an oven at 338° F.
*Yolks 6 eggs
1 c. sugar
1 tbsp. lemon juice
Grated rind one-half lemon *Whites 6 eggs 1 c. flour (pastry)
1/4 tsp. salt
Beat yolks until thick and lemon-colored, add sugar gradually, and continue beating, using Dover egg-beater. Add lemon juice, rind, and whites of eggs beaten until stiff and dry. When whites are partially mixed with yolks, remove beater, and carefully cut and fold in flour mixed and sifted with salt. Bake one hour in a slow oven, in an angel-cake pan or deep narrow pan.
From the "Boston Cooking-School Cook Book." By Fannie M. Farmer.
* The eggs in this recipe may be reduced to four with good results.
While baking powders are now practically all made with soda as the carbonate, many different substances are used for acid. There are three distinct types of powders, classified according to their composition. The oldest type is made with cream of tartar. This is a substance which is found abundantly in grape juice. If grape juice stands in wooden kegs, cream of tartar crystallizes out in masses on the inside. This crude substance, argol as it is called, is then purified by being dissolved in water, filtered, often through bone black, so as to remove the coloring matter of the grapes, and then re-crystallized and ground. It makes a good baking powder, because it is not easily soluble in water and does not need much "filler" to keep it dry. When it acts with the soda, besides the carbon dioxide another substance, known as Rochelle salts, is formed. This substance is used as a purgative in medicine, but so little of it results from the amount of baking powder ordinarily used in cooking that probably it has little effect on the human system.
Phosphate powders, a second type of baking powder, are usually made with acid calcium phosphate. These powders give a good deal of gas, but the gas is evolved very quickly. More filler is used because of this. The residue, like that of the tartrate powders, is also purgative, but probably no action is caused from the amount usually eaten.
The third class, alum powders, contains most commonly potash alum, that is, potassium aluminum sulphate, and, since alum is very soluble, even more filler is used than in the phosphate powders. In these powders the evolution of gas is much more continuous than in the phosphate types. Much objection has been made to these powders, because it was feared there might be injurious effects from the alum used. Repeated experiments do not seem, however, to show that the residues here are any more harmful than in the other cases. Manufacturers of tartrate powders have done their best to prove alum powders injurious because, as alum is much less expensive than cream of tartar, these last powders are naturally much cheaper.
Besides these three distinct types, there are mixed powders in which more than one acid is used. Alum is sometimes mixed with the phosphate powders to make the evolution of gas more continuous. Tartaric acid it-self often takes the place of a part of the cream of tartar in a tartrate powder. Probably the truth of the matter is that too much of them is not good for digestion, but that, as ordinarily used, they are all harmless. Nor do we ordinarily make much account of the difference in ingredients in our actual use of baking powders.
Sometimes, instead of baking powder, cream of tartar and soda are used. For one teaspoon of soda two slightly rounded teaspoons of cream of tartar are allowed. This does not give such good results as are obtained with purchased baking powders, because the measuring of the soda and acid is not nearly so accurate, nor is the mixing so thorough. Some recipes for home-made powders call for as many as a dozen siftings and are, therefore, rather laborious to make.
Since over two parts of cream of tartar are used for one of soda, and since in tartrate baking powder there is also some filler present, ranging from seven to about twenty per cent, it will be seen that only about one-fourth of the baking powder is soda. If, therefore, we wish to substitute baking powder and sweet milk for soda and sour milk, about four times as much baking powder as soda must be used.
1. Find out the cost per pound of baking powders of the different types found on your market.
2. What are the regulations in regard to baking powders for sale in interstate commmerce?
3. Have you state or city regulations in regard to baking powders?
4. Correct the following recipe for sour-milk gingerbread by calculating the amount of soda to use with this amount of molasses, and with the amount of sour milk. Subtract the sum from the amount of soda given in the recipe. What is the amount of the extra soda? How much baking powder will you add to replace the extra amount?
1 c. molasses 1 c. sour milk 2 1/2 c. flour
1 3/4 tsp. soda 2 tsp. ginger 1/2 tsp. salt
1/4 c. melted butter
5. What is the leavening in sponge cake? Why does it need a cooler oven than ordinary cake?