How do baking powder and soda work to leaven quick breads?

Leavening agents are substances that cause dough to rise. This can be achieved through the production of gas, which creates bubbles that expand during heating, or by the expansion of steam as the dough heats up.

In quick breads, where there is no yeast present to produce carbon dioxide through fermentation, chemical leavening agents such as baking powder or baking soda are used instead.

Here is how they work:

- Baking soda (sodium bicarbonate) is a base that when combined with an acid, releases carbon dioxide gas. When baking soda is added to a dough, it reacts with the acidic ingredients present, such as buttermilk, yogurt, sour cream, or even the natural acidity in some fruits and cocoa, to produce carbon dioxide bubbles that cause the dough to rise.

- Baking powder is a combination of baking soda, a dry acid (such as cream of tartar or sodium acid pyrophosphate), and a filler (usually cornstarch). When baking powder comes into contact with moisture, the acid reacts with the baking soda to release carbon dioxide. The filler serves to keep the ingredients separate until they are mixed with liquid, preventing premature release of carbon dioxide and ensuring that the baking powder will still be effective when used in a recipe.

These chemical leavening agents, when properly used, help quick breads rise and give them their characteristic fluffy texture. However, it's crucial to follow the recipe instructions carefully regarding the amount and type of leavening agent used, as incorrect usage can result in overly dense or flat breads.