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What is Baking Soda?

Definition, how baking soda works, and when it is used.


Tablespoon with Baking Soda
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Baking soda is one of the most widely used leaveners in baked goods. This simple chemical compound, also known as sodium bicarbonate, is found in crystalline form in nature, but is ground to a fine powder for use in cooking.

How Does Baking Soda Work?

Baking soda is an alkaline compound that, when combined with an acid, will produce carbon dioxide gas. The small bubbles of carbon dioxide gas become trapped in batter, causing it to inflate, or rise. Common acids used to cause this reaction include vinegar, lemon juice, buttermilk, yogurt, and cream of tartar.

Baking soda will also produce gas upon decomposition caused by heat. No acid is necessary for this reaction to take place, only exposure to temperatures above 80 degrees Celsius (176 degrees Fahrenheit).

When is Baking Soda Used?

Baking soda is used to leaven many “quick breads” like pancakes, muffins, cakes, and fried foods. These batters are not strong enough to hold shape for the length of time that it takes for yeast to create gas. Because baking soda produces gas quickly, it is not necessary to let the batter rise for long periods as with yeast breads. When the batter is exposed to heat, it becomes ridged and the expansion caused by the gas bubbles is set in place.

If a batter containing baking soda is left to sit at room temperature, it will begin to rise slowly and become slightly fluffy as the acids and bases react in the batter. The second, more dramatic rise occurs in the oven when the batter is exposed to heat. Heat accelerates the acid base reaction as well as causes decomposition of the baking soda, both of which produce the leaving gas. The leavening action of baking soda is often so rapid that it can be observed in real time.

How to Tell Baking Soda is Fresh

Because baking soda can decompose over time, you may want to test the potency of your baking soda. To test baking soda, simply add a pinch of baking soda to a small amount of vinegar in a bowl. If it foams vigorously, the baking soda is still active. This reaction can create a great deal of foam so be sure to do this over a sink.

Baking Soda vs Baking Powder

While baking soda is strictly an alkaline compound, baking powder is sodium bicarbonate already combined with an acid. The acid compound in baking powder is in the form of a salt, which means it will not react with the base until a liquid is added. Baking soda is good to use in recipes which include other acidic ingredients. If a recipe does not contain enough acids, using baking powder is appropriate as it contains its own acid. Using baking soda in alkaline recipes may also yield a bitter taste as there is not enough acid to neutralize the alkaline sodium bicarbonate.

Many recipes call for both baking soda and baking powder to provide maximum leavening action, but the ratio will depend on the relative acidity of the other ingredients.

Other Uses for Baking Soda

Baking soda is well known for its ability to absorb odors. For this reason, baking soda is often placed in refrigerators, freezers, and other enclosed spaces to absorb erroneous odors. Baking soda is also a favored cleaner because of its granular texture, which aids scrubbing and its alkaline pH which can dissolve some deposits and build-up.

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