Bubbling Baking Soda

• Like yeast, baking soda acts as a leavening agent. This means it helps dough to rise in the baking process. It reacts quickly with acidic ingredients such as buttermilk or lemon juice to create little bubbles of carbon dioxide gas. This gas stretches out the dough, causing it to rise. Because this process happens much faster than it does with yeast, baking soda is often used to make light, brittle or crunchy goods, such as biscuits and crusty soda bread. Bagels are neither brittle nor crunchy, so soda does not work well.

Feast on Yeast

• While bagel dough doesn't need as long to rise as some other yeast breads, it does need the slow action of yeast. Yeast is made up of millions of tiny organisms that feed on the sugars found in bread flour. As they feed, they release carbon dioxide. Gluten, a protein found in wheat flour, helps trap the gas in the dough. This action is slower than with baking soda. The yeast also imparts a distinct flavor to the dough that soda just can't match.

Bagels Need Patience

• With baking soda you can whip up a soda bread that's ready to eat in a few hours. Making bagels with yeast takes much longer. For example, after mixing and shaping, bagels need around 12 hours or more in the refrigerator, according to master breadmaker Peter Reinhart, writing on epicurious.com. This "retards" the dough and keeps it dense, tight and moist. When they're ready to dunk in boiling water, bagels need only around a minute on each side.

Something in the Water

• While baking soda may not be a suitable substitute for yeast, it still has a place in bagel making. Add a teaspoon of baking soda to the water bath to create a browner crust and slightly alkaline taste, much like that from bagel shop versions. A little molasses in the water also helps to create a good glaze that's sticky enough to hold toppings like sesame or poppy seeds you may choose to add.