Baking soda, or bicarbonate of soda, is usually used in baking for leavening purposes. The baking soda reacts with acidic ingredients in the recipe to help the product rise. This occurs because baking soda is on the basic side of the ph scale, and when it combines with an ingredient on the acidic side of the ph scale, it bubbles and causes the food to rise.
Recipes that call for baking soda usually also have an acidic ingredient included. Examples of acidic ingredients include vinegar, lemon juice, or butter milk. Because of this, it is best to use baking soda in recipes that call for it. If you do not have baking soda, you can still complete a recipe you have started without it, as long as you have a baking soda substitute handy.
Baking powder is another leavening agent used in recipes. Although it is not the same chemical mixture as baking powder, it does act in a similar manner. You can substitute baking powder in most recipes to replace baking soda, if you understand the principles involved.
Baking powder is made up of sodium bicarbonate, cream of tartar, and starch. The cream of tartar is the acidic part of the mixture, and the sodium bicarbonate is the basic. Together they create the chemical reaction that you need to produce light, fluffy baked products, such as cookies and quick breads. The starch is there as a drying agent, to prevent the two active ingredients from reacting before they are used in a recipe. Baking powder that has gotten wet or damp will no longer work, as the chemical reaction has already occurred.
If you have to use baking powder for a baking soda substitute, be aware that the results of your recipe will vary a bit from the base recipe. This is because baking soda, as a basic, has a distinctive taste. In fact, too much baking soda in a recipe will often result in a bitter flavor, as if you got a cleaning product in the recipe on accident. Baking powder, on the other hand, has both the acidic (cream of tartar) and the basic (sodium bicarbonate) properties mixed in correct proportion, resulting in a neutral taste.
Substituting baking powder for baking soda will result in a bland taste in some recipes. Adding other flavorings such as vanilla may help restore flavor intensity. You may also want to adjust the acidic ingredients that are included in the recipe. Remember that the baking soda would have counteracted the acidic taste, and that the baking powder will not work as well to balance the acids. Making adjustments such as using milk instead of buttermilk, or reducing the amounts of vinegar or lemon juice that are used may help the overall flavor of the finished product.
To use baking powder as a substitute for baking soda, you would replace the baking soda with 2-3 times more baking powder as a baking soda substitute. Making a recipe that called for 1 tsp of baking soda, you would use 2-3 tsp of baking powder. The heavier the batter or dough you are working with the more baking powder you would need. You would also use more baking powder for a lighter, fluffier finished product.
Baking recipes are built on the chemical reaction of the ingredients that you use. Although following the exact parameters of a baking recipe will usually yield the best results, it is possible to make substitutions. Understanding how baking soda and baking powder work with other ingredients in a recipe will help you learn the appropriate way to substitute them as necessary.