It is often necessary to substitute one ingredient for another in a recipe. Many different leavening agents are available and choosing a substitute for baking soda requires considering the roles that all the ingredients play in the recipe. Substituting the wrong ingredient or omitting baking soda from recipes may alter the color, texture or flavor of your finished baked product and make it less tender.
Identification
Baking soda, also known as bicarbonate of soda, helps baked goods rise due to its alkaline content. When mixed with acidic ingredients such as vinegar, buttermilk, sour cream or molasses, baking soda reacts by releasing bubbles of carbon dioxide that become trapped inside the batter. The result is a light and porous mixture.
Baking Powder
Baking powder is a combination of baking soda and a powdered acid. To replace 1 tsp. of baking soda, use 2 tsp. double-acting baking powder, which contains cornstarch as a filler, calcium phosphate and sodium aluminum sulfate in addition to baking soda. It is important to replace the acidic liquid ingredient in your recipe, such as lemon juice, molasses or buttermilk, with non-acidic liquids, such as sugar, regular milk or water. Too much acid in your recipe will prevent your baked goods from rising and the result will be a heavy, tough product.
Potassium Bicarbonate
Potassium bicarbonate often serves as a substitute for baking soda in sodium-restricted diets. To replace baking soda called for in your recipe, use an equal amount of potassium bicarbonate. You can often find potassium bicarbonate in the pharmacy section of your supermarket marketed under the name of bicarbonate or in a home brewery supply store.
Potash
Potash, or potassium carbonate, is an acceptable substitute for baking soda. It is sometimes used in gingerbread and honey cake recipes and available in German markets. A purified version of potash, called pearl ash, was primarily used in the 17th and 18th centuries but the practice was discontinued because of its bitter aftertaste. In "A Comparison of Leavening Agents," David Manthey found dough made from homemade potash was nearly identical to that of a baking soda biscuit.
