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Leavening Agents (To leaven is to cause to rise)

To leaven is to cause to rise or to make light. Unless something is added to a flour mixture to make it light and porous the digestive juices will not be able to penetrate it and it will be hard to digest. It will also be less palatable. Methods of Making Batters Light.

There are a number of materials that are used for this purpose. Probably the first used was air which was beaten into the mixture itself or into eggs before they were added to the batter. When the batter was baked the bubbles of air expanded, the gluten of the flour and the albumen of the eggs kept the air from escaping from the mixture. As it expanded it pushed the batter up with it; then when the heat was sufficient to cook the dough, the walls of the little cells formed by the air bubbles became firm enough to hold themselves up and the result was a light, porous loaf.

Probably the use of yeast came next. This is a rather slow process however, for it is necessary to wait for the yeast plant to grow and form enough bubbles of gas to make the bread rise. Scientists have discovered that these bubbles of gas can be produced instantly by putting together certain harmless chemicals and that the gas given off by these chemicals has the same effect on the bread (as far as making it light is concerned), as does that produced by the yeast plant.

One of these chemicals is baking soda, which will give off a gas called carbon dioxide gas when it is mixed with water and an acid. Soda combined with water only, will give off enough gas to raise the dough, but it will give a bitter taste and yellow color to the food. When the soda is combined with an acid in just the right proportion, the food will taste neither bitter nor sour. The acid has destroyed the bitter taste of the soda and the soda has destroyed the sour taste of the acid. If cream of tartar is the acid used there will be a substance called Rochelle salts formed. It will be in such small quantity that it will not be noticed in the food.

The acids usually used with soda in cooking are sour milk, molasses and cream of tartar or tartaric acid. Some very old cook books use a few spoonfuls of vinegar with the soda. Baking Powder.

Soda and cream of tartar used to be kept separate and combined as needed by the house-wife. Because of the difficulty of measuring the correct proportion of each ingredient we more often now use what we call baking powder. Baking powder is made of soda and cream of tartar carefully weighed and thoroughly mixed and sifted, with enough corn starch mixed with them to keep the powder from absorbing moisture and losing strength.

Sometimes acid phosphate, alum and other cheap acids are used in the manufacture of baking powders. The acid phosphate makes a very good baking powder but alum baking powder and all cheap powders should be avoided. They are not cheap in the long run.

Experiments.

Ex. 1. Put into a test tube 1/6 t. baking soda and pour + C. hot water on it. The foaming is caused by the gas that is being given off.

Ex. 2. Put into a test tube 1/6 t. soda and add 2 T. cold water. Very little gas is given off.

Ex. 3. Put a little more than 3 t. cream of tartar into another tube with 2 T. cold water. Stir until dissolved. Very little gas is given off.

Ex. 4. Mix the contents of the last two tubes together. The foaming shows that gas is being given off.

Ex. 5. Heat the tube gently. More gas is given off.

Ex. 6. Add t. soda to glass sour milk. Add 1 t. soda to 4 glass of New Orleans molasses. Notice the bubbles that form in both glasses, showing that gas is being given off. General Proportions of Cream of Tartar, Molasses, and Sour Milk to be used with Soda: 1 t. soda to 24 t. cream of tartar. t. soda to 2 C. thick sour milk. 1 t. soda to 1 C. New Orleans molasses.

If your recipe calls for sweet milk and baking powder and you wish to use sour milk and soda, allow t. soda to each cup of sour milk. Each t. soda will make 1 C. flour light. For each additional cup of flour add 2 t. baking powder. From 1½ t. to 2 t. baking powder is the amount usually allowed for each cup of flour. The more eggs used, the less baking powder will be needed, as the eggs hold the air which is beaten into the mixture.

Batters made light by any of the quick leavening agents should be baked as soon as they are mixed to prevent the escape of the gas.

Baking Powder.