Protein powder can be used as a partial substitute for flour in baking, but it is not a direct 1:1 replacement. Flour provides structure and stability to baked goods, while protein powder provides protein.
The specific type of protein powder and the desired outcome of the baked goods will determine how much and what type of protein powder can be substituted for flour. For example, using whey protein powder in a cake recipe may result in a denser, drier final product. Using a plant-based protein powder, such as pea protein powder, may result in a final product that is more dense and gummy.
It is important to note that substituting too much protein powder for flour in a recipe may result in a final product that is not desirable in texture, taste, or appearance. It is best to start with small substitutions and adjust as needed. There are also recipes specifically designed for using protein powder as a flour substitute, and these may be a good starting point.