No, powdered sugar and flour cannot be directly substituted for each other in recipes. They serve different purposes and have different properties that would significantly affect the outcome of the final product.
Texture: Powdered sugar is very fine and contains a small amount of cornstarch, which prevents it from clumping. Flour, on the other hand, has a coarser texture and does not contain cornstarch. Substituting powdered sugar for flour would likely result in a very different texture in the baked goods, and it may not hold together properly.
Sweetness: Powdered sugar is primarily used for its sweetness and is not suitable for providing the structure and volume that flour contributes in baking. If you use powdered sugar instead of flour, the baked goods will be overly sweet and lack the structure necessary for the recipe.
Thickening and Binding: Flour is often used as a thickening agent and provides binding properties in recipes. Powdered sugar lacks these properties, so using it as a substitute for flour would likely result in a runny or loose texture in the baked goods.
Gluten Formation: Flour contains proteins that, when combined with liquid and kneaded or mixed, form gluten. This gluten formation provides structure and elasticity to baked goods like bread and certain pastries. Powdered sugar does not contain these proteins, so using it instead of flour would not result in proper gluten development.
In summary, it's crucial to follow recipes as they are written and avoid substituting powdered sugar for flour or vice versa. If you need to make adjustments or substitutions in a recipe, it's best to look for alternative flours or other suitable ingredients specifically meant for that purpose. Making significant ingredient swaps without understanding the roles of each ingredient can lead to disappointing results in baking.