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"How do baking powder and baking soda work?"

What is the difference between baking soda and baking powder in their effects in making banana bread?


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Baking powder and baking soda both produce carbon dioxide, which helps raise or "leaven" baked products. Baking soda works best in conjunction with an acidic ingredient. In the case of banana bread, this may be buttermilk, brown sugar, molasses or the bananas themselves. Recipes generally include just enough baking soda to balance the acidity in the batter. For instance 1/4 teaspoon baking soda is balanced with 1/2 cup buttermilk, applesauce or mashed just-ripe banana (note that bananas become less acidic as they ripen). This produces sufficient carbon dioxide to raise one cup of flour.
This however, may not be sufficient to leaven the whole recipe. Here's where baking powder comes in. Baking powder contains both baking soda and a dry acidic ingredient. Since it isn't dependant on acid ingredients in the batter, it is used to add the extra leavening necessary to raise the rest of the batter. Generally one teaspoon of baking powder leavens one cup of flour. In the case of recipes like banana bread which contain heavy ingredients, such as bananas and sometimes heavy grains like wheat germ or whole wheat flour, this may be increased to 1 1/2 or 2 teaspoons of baking powder per cup of flour.


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