Flour's Purpose

• Flour, as a thickener in a stew, is generally used in one of three methods. The beef cubes are coated in flour and browned lightly in oil before making the stew. Another option is to make a roux by whisking flour into hot, melted butter. Beef broth is then added to this roux and slowly thickened into a gravy. The final method is known as a beurre manie, and is similar to a roux. Softened butter and flour in equal quantities are whisked together to make a paste, and then added to a stew during the final stages of cooking.

Baking Soda's Role

• Baking soda, made from sodium bicarbonate derived from trona ore, is an alkaline substance known for its ability to produce carbon dioxide bubbles and leaven baked goods. Although similar in appearance to flour, it does not perform like flour in any respect. It will not thicken a beef stew and may add a bitter, soapy flavor. Do not add it to a stew in place of flour.

In Small Amounts

• Baking soda -- or more likely, baking powder -- is sometimes added to flour when dredging meat to lighten the breading and make it crispy. If you'd like to use baking soda in this way, add 1/4 teaspoon of baking soda for each 1 cup of flour. Remember, though, that baking soda needs an acidic ingredient to neutralize its alkalinity and bitter taste and to start the reaction. To provide the necessary acidity, marinate the stew meat in buttermilk or add molasses, brown sugar or another acidic ingredient to the stew. Baking powder, which already contains an acidic ingredient, is more forgiving and requires no additional ingredients. Use it at a ratio of 1 teaspoon baking powder per 1 cup of flour.

Flour Alternatives

• Although you can't use baking soda as an alternative for flour when making stew, you've got plenty of other options. Thicken the stew at the end of the cooking time with cornstarch mixed in cold water, or use arrowroot, potato starch or tapioca. Even a bit of masa or cornmeal added to the stew will help thicken it. Try breading stew meat in sweet rice flour or finely ground cereal instead of flour.