Leavening is an agent that produces fermentation. The leavening agent produces gas, air, or steam that expands when heated, making the resulting product light and altering grain textures.
Leavening agents include YEAST, BAKING POWDER, and BAKING SODA with a little food acid. Yeast is a small plant that, if mixed with sugar, will produce carbon dioxide whenever temperature and moisture are right. Baking powder produces a chemical reaction that releases some of its gas when mixed with a liquid and the rest of the gas whenever it is heated. The following are descriptions of products and their category:
BAKING SODA-- is an important ingredient of baking powder. To be used as leaven it must be mixed with a food acid like buttermilk, sour milk, molasses, vinegar, lemon juice, or cream of tartar.
CREAM OF TARTAR-- by itself does not leaven anything any more than does sour milk or buttermilk. It is often used as a flavoring in foods and beverages.
BREWER'S YEAST --is a by-product of the fermentation of beer and is a rich source of vitamins, especially the B-complex. It has no leavening properties.
YEAST EXTRACT-- is an ingredient used in canned or in dehydrated soups. It is only an extract and cannot leaven anything.
EGG WHITES--While eggs are not considered leavening agents, the egg whites, when beaten, can leaven by expansion of the air and by steam when heated. They are the only leavening in many angel food cakes.
