Yes, you generally need to double the amount of baking powder, baking soda, and yeast when doubling a recipe. However, be mindful of potential over-leavening, especially with yeast in longer fermentation recipes.
When scaling a baking recipe, it's crucial to maintain the correct ratios of ingredients to ensure the final product has the desired texture, rise, and flavor. Leavening agents like baking powder, baking soda, and yeast are responsible for creating air bubbles in the batter or dough, which results in a light and airy texture.
Baking Powder and Baking Soda: These chemical leaveners react to produce carbon dioxide gas. If you double the recipe, you need to double the amount of baking powder or baking soda to generate the same amount of gas relative to the increased volume of other ingredients. Failing to do so will result in a flat or dense baked good.
Yeast: Yeast is a biological leavening agent that ferments sugars to produce carbon dioxide. Similar to baking powder and baking soda, doubling the recipe generally requires doubling the yeast. However, yeast activity is also affected by temperature and time. In recipes with long fermentation times (e.g., sourdough), doubling the yeast might lead to over-proofing, resulting in a collapsed or sour-tasting final product. In such cases, you might slightly reduce the doubled amount of yeast, especially if the fermentation time is significantly extended. Monitor the dough closely during proofing.
In summary, while a one-to-one doubling of leavening agents is usually correct, always consider the specific recipe and adjust slightly if necessary, especially with yeast in long-fermentation recipes.
When scaling recipes, especially those involving yeast, it's often better to slightly under-leaven than over-leaven. You can always allow for a longer proofing time if the dough is rising slowly, but you can't undo over-proofing.