CHEMICAL LEAVENING AGENTS Leavening Leavening means to lighten. It is a process in which bubbles of gas cause the mixture to inflate and that shape maintain even after the baking process. Main gasses that leaven are: Air, Carbon Dioxide and Steam. Air and steam naturally occur and Carbon dioxide is produced by chemicals. Leavening Agents Agents that are responsible for leavening are called as leavening agents. Leavening agents are most often used in quick breads.

Types Of Leavening Agents There are two types of leavening agents:  Organic / Biological Leavening Agents (Yeast)  Chemical Leavening Agents Chemical Leavening Agents: There are three main chemical leavening agents that are used: 1) Baking Soda 2) Baking Powder 3) Ammonium Bicarbonate 1) Baking Soda

Baking soda is a base and contains Sodium bicarbonate (NaHCO3). Baking soda releases sodium carbonate as well as carbon dioxide when heated. Sodium carbonate gives food a bad taste and a yellowish color. However, baking soda is always used with an acid, which alters the chemical reaction to prevent sodium carbonate from forming. Some examples of acid are buttermilk, vinegar, lemon juice, molasses, honey, Vinegar, Buttermilk, Cocoa fruits, fruit juices, and cream of tartar. 2) Baking Powder Leavening compound that contain baking soda, dry acids and starch or some other filler. The filler in baking powder, usually cornstarch or calcium carbonate, absorbs moisture in the air, which helps prevent a chemical reaction from taking place too soon. Most commercially available baking powders are made up of sodium bicarbonate (also known as baking soda or bicarbonate of soda) and one or more acid salts. Typical formulations (by

1

weight) call for 30% sodium bicarbonate, 5-12% monocalcium phosphate, and 21- 26% sodium aluminium sulfate. The last two are acidic. Baking powder comes in two types:  Single-Acting Baking Powder As soon as liquid is added, carbon dioxide starts to be released. The quick reaction occurs because the acid in baking powder is soluble in a cold liquid. Common low- temperature acid salts include cream of tartar and monocalcium phosphate (also called calcium acid phosphate).  Double-Acting Baking Powder Usually preferred, contains two acids, one that reacts with cold liquid and one that reacts with heat. Some carbon dioxide is released as soon as liquid is added, but most is produced as the batter heats in the oven. High-temperature acid salts include sodium aluminium sulfate, sodium aluminum phosphate, and sodium acid pyrophosphate. Strength of Baking Powder By federal law, baking powder must yield at least 12% of carbon dioxide, most home used are at 14%. Too much baking powder will cause the walls of the flour mixture to stretch too far, break, and collapse. Too little will mean a compact product. 3) Ammonium Bicarbonate Baking soda and baking powder are the most common chemicals used to produce

carbon dioxide, however ammonium bicarbonate (NH4CO3) can be used. a. Ammonium bicarbonate produces carbon dioxide as it decomposes. b. Mostly used in crackers and certain types of cookies because of the affect to taste.

2